diff --git a/exec/bootstrap.php b/exec/bootstrap.php
index f4ea95b..05633d7 100644
--- a/exec/bootstrap.php
+++ b/exec/bootstrap.php
@@ -20,6 +20,8 @@ foreach ([
     'CsrfGuard.php',
     'RuleRepository.php',
     'DirectAdminSyncRepository.php',
+    'DirectAdminVacationApi.php',
+    'DirectAdminVacationSyncService.php',
     'RuleValidator.php',
     'MailboxDirectory.php',
     'AuditLog.php',
diff --git a/exec/handlers/_form_helpers.php b/exec/handlers/_form_helpers.php
index 8b1fadd..73c1056 100644
--- a/exec/handlers/_form_helpers.php
+++ b/exec/handlers/_form_helpers.php
@@ -41,10 +41,22 @@ function normalize_rule_post(array $post): array
     return $post;
 }
 
+/** @param array<string,mixed> $rule @return array<string,mixed> */
+function attach_rule_scope(AppContext $ctx, array $rule): array
+{
+    if (empty($rule['dynamic_scope'])) {
+        $rule['mailbox_snapshot'] = (new MailboxDirectory())->mailboxesForUser($ctx->daUser->username());
+    }
+    return $rule;
+}
+
 function render_calendar_picker(AppContext $ctx, string $name, string $title, string $value): string
 {
     $mode = $ctx->settings->scheduleMode();
     $selectedDate = substr($value, 0, 10);
+    if (!preg_match('/^[0-9]{4}-[0-9]{2}-[0-9]{2}$/', $selectedDate)) {
+        $selectedDate = date('Y-m-d');
+    }
     $selectedTime = '09:00';
     $selectedPeriod = 'morning';
     if ($mode === 'exact_hour' && preg_match('/T([0-9]{2}:[0-9]{2})$/', $value, $m)) {
@@ -52,33 +64,62 @@ function render_calendar_picker(AppContext $ctx, string $name, string $title, st
     } elseif ($mode === 'directadmin_period' && preg_match('/\|(morning|afternoon|evening)$/', $value, $m)) {
         $selectedPeriod = $m[1];
     }
-    $days = '';
-    for ($week = 0, $day = 1; $week < 4; $week++) {
-        $days .= '<tr>';
-        for ($i = 0; $i < 7; $i++, $day++) {
-            $date = sprintf('2026-06-%02d', $day);
-            $class = $date === $selectedDate ? ' is-selected' : '';
-            $days .= '<td><button type="button" class="br-cal-day' . $class . '" data-date-target="' . AppContext::e($name . '_date') . '" data-date-label="' . AppContext::e($name . '_label') . '" data-date-value="' . AppContext::e($date) . '">' . $day . '</button></td>';
-        }
-        $days .= '</tr>';
-    }
+    $selectedDt = DateTimeImmutable::createFromFormat('!Y-m-d', $selectedDate) ?: new DateTimeImmutable('today');
+    $monthStart = $selectedDt->modify('first day of this month');
+    $days = render_calendar_days($name, $selectedDate, $monthStart);
+    $visibleMonth = $monthStart->format('Y-m');
+    $monthLabel = calendar_month_label($ctx, $monthStart);
     if ($mode === 'exact_hour') {
-        $timeControl = '<label>' . AppContext::e($ctx->t('Time')) . '</label><input type="time" name="' . AppContext::e($name . '_time') . '" value="' . AppContext::e($selectedTime) . '" step="60">';
+        $timeControl = '<label>' . AppContext::e($ctx->t('Time')) . '</label><input type="time" name="' . AppContext::e($name . '_time') . '" value="' . AppContext::e($selectedTime) . '" step="60" data-time-for="' . AppContext::e($name) . '">';
     } else {
-        $timeControl = '<label>' . AppContext::e($ctx->t('Time of day')) . '</label><select name="' . AppContext::e($name . '_period') . '">' .
+        $timeControl = '<label>' . AppContext::e($ctx->t('Time of day')) . '</label><select name="' . AppContext::e($name . '_period') . '" data-period-for="' . AppContext::e($name) . '">' .
             '<option value="morning"' . ($selectedPeriod === 'morning' ? ' selected' : '') . '>' . AppContext::e($ctx->t('Morning')) . '</option>' .
             '<option value="afternoon"' . ($selectedPeriod === 'afternoon' ? ' selected' : '') . '>' . AppContext::e($ctx->t('Afternoon')) . '</option>' .
             '<option value="evening"' . ($selectedPeriod === 'evening' ? ' selected' : '') . '>' . AppContext::e($ctx->t('Evening')) . '</option>' .
             '</select>';
     }
-    return '<div class="panel"><h3>' . AppContext::e($title) . '</h3><div class="br-restore-layout"><div class="br-restore-calendar"><h4>' . AppContext::e($title) . '</h4><div class="br-month-nav"><button type="button" class="br-month-btn">&lsaquo;</button><span class="br-month-label">Czerwiec 2026</span><button type="button" class="br-month-btn">&rsaquo;</button></div>' .
-        '<table class="br-calendar-grid"><thead><tr><th>Pn</th><th>Wt</th><th>Śr</th><th>Cz</th><th>Pt</th><th>Sb</th><th>Nd</th></tr></thead><tbody>' . $days . '</tbody></table>' .
+    return '<div class="panel"><h3>' . AppContext::e($title) . '</h3><div class="br-restore-layout"><div class="br-restore-calendar" data-calendar-picker data-schedule-mode="' . AppContext::e($mode) . '" data-calendar-name="' . AppContext::e($name) . '" data-visible-month="' . AppContext::e($visibleMonth) . '" data-selected-date="' . AppContext::e($selectedDate) . '"><h4>' . AppContext::e($title) . '</h4><div class="br-month-nav"><button type="button" class="br-month-btn" data-calendar-prev>&lsaquo;</button><span class="br-month-label" data-calendar-month-label>' . AppContext::e($monthLabel) . '</span><button type="button" class="br-month-btn" data-calendar-next>&rsaquo;</button></div>' .
+        '<table class="br-calendar-grid"><thead><tr><th>Pn</th><th>Wt</th><th>Śr</th><th>Cz</th><th>Pt</th><th>Sb</th><th>Nd</th></tr></thead><tbody data-calendar-days>' . $days . '</tbody></table>' .
         '<div class="br-date-label" id="' . AppContext::e($name . '_label') . '">Wybrano: ' . AppContext::e($selectedDate) . '</div><input type="hidden" id="' . AppContext::e($name . '_date') . '" name="' . AppContext::e($name . '_date') . '" value="' . AppContext::e($selectedDate) . '"></div>' .
         '<div class="br-restore-calendar"><h4>' . AppContext::e($ctx->t('Time')) . '</h4>' . $timeControl . '</div></div>' .
-        '<input type="hidden" name="' . AppContext::e($name) . '" value="' . AppContext::e($value) . '"></div>';
+        '<input type="hidden" id="' . AppContext::e($name) . '" name="' . AppContext::e($name) . '" value="' . AppContext::e($value) . '" data-canonical-value="' . AppContext::e($name) . '"></div>';
 }
 
 function render_preview_box(array $rule): string
 {
     return '<div class="preview-box"><div><strong>Temat:</strong> ' . AppContext::e((string)$rule['subject']) . '</div><br><div>' . nl2br(AppContext::e((string)$rule['body'])) . '</div></div>';
 }
+
+function render_calendar_days(string $name, string $selectedDate, DateTimeImmutable $monthStart): string
+{
+    $offset = ((int)$monthStart->format('N')) - 1;
+    $daysInMonth = (int)$monthStart->format('t');
+    $html = '';
+    $day = 1;
+    for ($week = 0; $week < 6; $week++) {
+        $html .= '<tr>';
+        for ($i = 0; $i < 7; $i++) {
+            if (($week === 0 && $i < $offset) || $day > $daysInMonth) {
+                $html .= '<td class="br-cal-empty"></td>';
+                continue;
+            }
+            $date = $monthStart->setDate((int)$monthStart->format('Y'), (int)$monthStart->format('m'), $day)->format('Y-m-d');
+            $class = $date === $selectedDate ? ' is-selected' : '';
+            $html .= '<td><button type="button" class="br-cal-day' . $class . '" data-date-target="' . AppContext::e($name . '_date') . '" data-date-label="' . AppContext::e($name . '_label') . '" data-date-value="' . AppContext::e($date) . '">' . $day . '</button></td>';
+            $day++;
+        }
+        $html .= '</tr>';
+        if ($day > $daysInMonth) {
+            break;
+        }
+    }
+    return $html;
+}
+
+function calendar_month_label(AppContext $ctx, DateTimeImmutable $monthStart): string
+{
+    $pl = ['Styczeń', 'Luty', 'Marzec', 'Kwiecień', 'Maj', 'Czerwiec', 'Lipiec', 'Sierpień', 'Wrzesień', 'Październik', 'Listopad', 'Grudzień'];
+    $en = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
+    $months = $ctx->lang->code() === 'pl' ? $pl : $en;
+    return $months[((int)$monthStart->format('n')) - 1] . ' ' . $monthStart->format('Y');
+}
diff --git a/exec/handlers/create.php b/exec/handlers/create.php
index f120008..5d69f1e 100644
--- a/exec/handlers/create.php
+++ b/exec/handlers/create.php
@@ -7,8 +7,9 @@ return static function (AppContext $ctx): void {
         try {
             $ctx->requireCsrf('create');
             $input = normalize_rule_post($_POST);
-            $rule = RuleValidator::validate($input, $ctx->settings);
+            $rule = attach_rule_scope($ctx, RuleValidator::validate($input, $ctx->settings));
             $ctx->rules->create($ctx->daUser->username(), $rule);
+            $ctx->syncActiveBackend();
             Http::redirect($ctx->url('index.html', ['status' => 'created']));
         } catch (Throwable $e) {
             $errors[] = $e->getMessage();
diff --git a/exec/handlers/delete.php b/exec/handlers/delete.php
index a50ed1e..a37462b 100644
--- a/exec/handlers/delete.php
+++ b/exec/handlers/delete.php
@@ -12,6 +12,7 @@ return static function (AppContext $ctx): void {
         try {
             $ctx->requireCsrf('delete:' . $id);
             $ctx->rules->delete($ctx->daUser->username(), $id);
+            $ctx->syncActiveBackend();
             $ctx->audit->record('delete', $ctx->daUser->username(), ['rule_id' => $id, 'subject' => (string)$rule['subject']]);
             Http::redirect($ctx->url('index.html', ['status' => 'deleted']));
         } catch (Throwable $e) {
diff --git a/exec/handlers/toggle.php b/exec/handlers/toggle.php
index d758ed1..c7869ee 100644
--- a/exec/handlers/toggle.php
+++ b/exec/handlers/toggle.php
@@ -10,5 +10,6 @@ return static function (AppContext $ctx): void {
         throw new RuntimeException($ctx->t('Rule not found'));
     }
     $ctx->rules->update($ctx->daUser->username(), $id, ['enabled' => empty($rule['enabled'])]);
+    $ctx->syncActiveBackend();
     Http::redirect($ctx->url('index.html', ['status' => 'toggled']));
 };
diff --git a/exec/handlers/update.php b/exec/handlers/update.php
index 114f6b5..8e06e94 100644
--- a/exec/handlers/update.php
+++ b/exec/handlers/update.php
@@ -13,8 +13,9 @@ return static function (AppContext $ctx): void {
         try {
             $ctx->requireCsrf('update:' . $id);
             $input = normalize_rule_post($_POST);
-            $patch = RuleValidator::validate($input, $ctx->settings);
+            $patch = attach_rule_scope($ctx, RuleValidator::validate($input, $ctx->settings));
             $ctx->rules->update($ctx->daUser->username(), $id, $patch);
+            $ctx->syncActiveBackend();
             Http::redirect($ctx->url('index.html', ['status' => 'updated']));
         } catch (Throwable $e) {
             $errors[] = $e->getMessage();
diff --git a/exec/lib/AppContext.php b/exec/lib/AppContext.php
index 2ef86bb..a7fbad6 100644
--- a/exec/lib/AppContext.php
+++ b/exec/lib/AppContext.php
@@ -70,6 +70,20 @@ final class AppContext
         }
     }
 
+    public function syncActiveBackend(): void
+    {
+        if ($this->settings->backendMode() !== 'da') {
+            return;
+        }
+        $service = new DirectAdminVacationSyncService(
+            $this->rules,
+            new DirectAdminSyncRepository(),
+            new MailboxDirectory(),
+            new DirectAdminVacationApi()
+        );
+        $service->syncUser($this->daUser->username());
+    }
+
     public function render(string $title, string $body, array $ok = [], array $errors = []): void
     {
         header('Content-Type: text/html; charset=UTF-8');
@@ -109,17 +123,89 @@ final class AppContext
     private function scripts(): string
     {
         $selectedLabel = json_encode($this->t('Selected'), JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT);
+        $monthNames = json_encode($this->lang->code() === 'pl'
+            ? ['Styczeń', 'Luty', 'Marzec', 'Kwiecień', 'Maj', 'Czerwiec', 'Lipiec', 'Sierpień', 'Wrzesień', 'Październik', 'Listopad', 'Grudzień']
+            : ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'], JSON_UNESCAPED_UNICODE | JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT);
         return <<<JS
 (function () {
   var selectedLabel = {$selectedLabel};
-  document.querySelectorAll('[data-date-value]').forEach(function (btn) {
+  var monthNames = {$monthNames};
+  function pad(value) { return value < 10 ? '0' + value : String(value); }
+  function updateCanonical(name) {
+    var date = document.getElementById(name + '_date');
+    var canonical = document.getElementById(name);
+    if (!date || !canonical) { return; }
+    var time = document.querySelector('[data-time-for="' + name + '"]');
+    var period = document.querySelector('[data-period-for="' + name + '"]');
+    if (time) {
+      canonical.value = date.value + 'T' + (time.value || '09:00');
+    } else if (period) {
+      canonical.value = date.value + '|' + (period.value || 'morning');
+    }
+  }
+  function bindDateButton(btn) {
     btn.addEventListener('click', function () {
       var target = document.getElementById(btn.getAttribute('data-date-target'));
       var label = document.getElementById(btn.getAttribute('data-date-label'));
       if (target) { target.value = btn.getAttribute('data-date-value') || ''; }
       if (label) { label.textContent = selectedLabel + ': ' + (btn.getAttribute('data-date-value') || ''); }
+      var calendar = btn.closest('[data-calendar-picker]');
+      if (calendar) { calendar.setAttribute('data-selected-date', btn.getAttribute('data-date-value') || ''); }
       btn.closest('.br-restore-calendar').querySelectorAll('.br-cal-day').forEach(function (d) { d.classList.remove('is-selected'); });
       btn.classList.add('is-selected');
+      if (calendar) { updateCanonical(calendar.getAttribute('data-calendar-name')); }
+    });
+  }
+  function renderMonth(calendar, year, month) {
+    var selected = calendar.getAttribute('data-selected-date') || '';
+    var tbody = calendar.querySelector('[data-calendar-days]');
+    var label = calendar.querySelector('[data-calendar-month-label]');
+    if (!tbody || !label) { return; }
+    var first = new Date(Date.UTC(year, month - 1, 1));
+    var offset = (first.getUTCDay() + 6) % 7;
+    var days = new Date(Date.UTC(year, month, 0)).getUTCDate();
+    var day = 1;
+    var html = '';
+    for (var week = 0; week < 6; week++) {
+      html += '<tr>';
+      for (var i = 0; i < 7; i++) {
+        if ((week === 0 && i < offset) || day > days) {
+          html += '<td class="br-cal-empty"></td>';
+          continue;
+        }
+        var value = year + '-' + pad(month) + '-' + pad(day);
+        var cls = value === selected ? ' is-selected' : '';
+        html += '<td><button type="button" class="br-cal-day' + cls + '" data-date-target="' + calendar.getAttribute('data-calendar-name') + '_date" data-date-label="' + calendar.getAttribute('data-calendar-name') + '_label" data-date-value="' + value + '">' + day + '</button></td>';
+        day++;
+      }
+      html += '</tr>';
+      if (day > days) { break; }
+    }
+    tbody.innerHTML = html;
+    label.textContent = monthNames[month - 1] + ' ' + year;
+    calendar.setAttribute('data-visible-month', year + '-' + pad(month));
+    tbody.querySelectorAll('[data-date-value]').forEach(bindDateButton);
+  }
+  document.querySelectorAll('[data-date-value]').forEach(function (btn) {
+    bindDateButton(btn);
+  });
+  document.querySelectorAll('[data-calendar-picker]').forEach(function (calendar) {
+    var name = calendar.getAttribute('data-calendar-name');
+    calendar.querySelectorAll('[data-calendar-prev],[data-calendar-next]').forEach(function (btn) {
+      btn.addEventListener('click', function () {
+        var parts = (calendar.getAttribute('data-visible-month') || '').split('-');
+        var year = parseInt(parts[0], 10);
+        var month = parseInt(parts[1], 10);
+        if (!year || !month) { return; }
+        month += btn.hasAttribute('data-calendar-next') ? 1 : -1;
+        if (month < 1) { month = 12; year--; }
+        if (month > 12) { month = 1; year++; }
+        renderMonth(calendar, year, month);
+      });
+    });
+    document.querySelectorAll('[data-time-for="' + name + '"],[data-period-for="' + name + '"]').forEach(function (control) {
+      control.addEventListener('change', function () { updateCanonical(name); });
+      control.addEventListener('input', function () { updateCanonical(name); });
     });
   });
 })();
diff --git a/exec/lib/DirectAdminSyncRepository.php b/exec/lib/DirectAdminSyncRepository.php
index fe05949..444e0a5 100644
--- a/exec/lib/DirectAdminSyncRepository.php
+++ b/exec/lib/DirectAdminSyncRepository.php
@@ -22,6 +22,12 @@ final class DirectAdminSyncRepository
         return array_values($data['rules'][$ruleId] ?? []);
     }
 
+    /** @return array<string,array<int,array<string,mixed>>> */
+    public function allRuleEntries(string $username): array
+    {
+        return $this->read($username)['rules'];
+    }
+
     /** @return array<int,array<string,mixed>> */
     public function deleteRuleEntries(string $username, string $ruleId): array
     {
diff --git a/exec/lib/DirectAdminVacationApi.php b/exec/lib/DirectAdminVacationApi.php
index b0d1236..93dc8cb 100644
--- a/exec/lib/DirectAdminVacationApi.php
+++ b/exec/lib/DirectAdminVacationApi.php
@@ -1,14 +1,18 @@
 <?php
 declare(strict_types=1);
 
-final class DirectAdminVacationApi
+class DirectAdminVacationApi
 {
-    public function __construct(private string $directadminBinary = '/usr/local/directadmin/directadmin')
+    /** @var callable|null */
+    private $request;
+
+    public function __construct(private string $daBinary = '/usr/local/bin/da', ?callable $request = null)
     {
+        $this->request = $request;
     }
 
     /** @param array<string,mixed> $rule @return array<string,string> */
-    public function buildSavePayload(string $email, array $rule): array
+    public function buildSavePayload(string $email, array $rule, bool $exists = true): array
     {
         if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
             throw new InvalidArgumentException('Invalid mailbox email');
@@ -16,20 +20,46 @@ final class DirectAdminVacationApi
         [$local, $domain] = explode('@', strtolower($email), 2);
         [$startDate, $startTime] = $this->splitPeriod((string)($rule['start_value'] ?? ''));
         [$endDate, $endTime] = $this->splitPeriod((string)($rule['end_value'] ?? ''));
+        [$startYear, $startMonth, $startDay] = explode('-', $startDate);
+        [$endYear, $endMonth, $endDay] = explode('-', $endDate);
         return [
-            'action' => 'modify',
+            'action' => $exists ? 'modify' : 'create',
             'domain' => $domain,
             'user' => $local,
             'email' => $email,
             'text' => (string)($rule['body'] ?? ''),
             'subject' => (string)($rule['subject'] ?? ''),
-            'startdate' => $startDate,
             'starttime' => $startTime,
-            'enddate' => $endDate,
+            'startyear' => $startYear,
+            'startmonth' => $startMonth,
+            'startday' => $startDay,
             'endtime' => $endTime,
+            'endyear' => $endYear,
+            'endmonth' => $endMonth,
+            'endday' => $endDay,
+            'create' => $exists ? '' : 'Create',
         ];
     }
 
+    /** @param array<string,mixed> $rule */
+    public function saveVacation(string $owner, string $email, array $rule, bool $exists): void
+    {
+        $this->requestAsUser($owner, 'CMD_API_EMAIL_VACATION', $this->buildSavePayload($email, $rule, $exists));
+    }
+
+    public function deleteVacation(string $owner, string $email): void
+    {
+        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
+            throw new InvalidArgumentException('Invalid mailbox email');
+        }
+        [$local, $domain] = explode('@', strtolower($email), 2);
+        $this->requestAsUser($owner, 'CMD_API_EMAIL_VACATION', [
+            'action' => 'delete',
+            'domain' => $domain,
+            'select0' => $local,
+        ]);
+    }
+
     /** @return array{0:string,1:string} */
     private function splitPeriod(string $value): array
     {
@@ -38,4 +68,58 @@ final class DirectAdminVacationApi
         }
         return [$m[1], $m[2]];
     }
+
+    /** @param array<string,string> $payload */
+    private function requestAsUser(string $owner, string $endpoint, array $payload): void
+    {
+        if (!preg_match('/^[A-Za-z0-9._-]+$/', $owner)) {
+            throw new InvalidArgumentException('Invalid DirectAdmin owner');
+        }
+        if ($this->request !== null) {
+            $result = call_user_func($this->request, $owner, $endpoint, $payload);
+            if ($result === false) {
+                throw new RuntimeException('DirectAdmin API request failed');
+            }
+            return;
+        }
+        $baseUrl = $this->apiUrl($owner);
+        $url = rtrim($baseUrl, '/') . '/' . $endpoint;
+        $args = ['curl', '-fsS', '-X', 'POST'];
+        foreach ($payload as $key => $value) {
+            $args[] = '--data-urlencode';
+            $args[] = $key . '=' . $value;
+        }
+        $args[] = $url;
+        $this->run($args, '');
+    }
+
+    private function apiUrl(string $owner): string
+    {
+        $output = $this->run([$this->daBinary, 'api-url', '--user=' . $owner], '');
+        $url = trim($output);
+        if ($url === '' || !preg_match('#^https?://#', $url)) {
+            throw new RuntimeException('Cannot determine DirectAdmin API URL for user');
+        }
+        return $url;
+    }
+
+    /** @param string[] $args */
+    private function run(array $args, string $stdin): string
+    {
+        $process = proc_open($args, [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']], $pipes);
+        if (!is_resource($process)) {
+            throw new RuntimeException('Cannot start DirectAdmin API command');
+        }
+        fwrite($pipes[0], $stdin);
+        fclose($pipes[0]);
+        $stdout = stream_get_contents($pipes[1]) ?: '';
+        $stderr = stream_get_contents($pipes[2]) ?: '';
+        fclose($pipes[1]);
+        fclose($pipes[2]);
+        $code = proc_close($process);
+        if ($code !== 0) {
+            throw new RuntimeException('DirectAdmin API command failed: ' . trim($stderr));
+        }
+        return $stdout;
+    }
 }
diff --git a/exec/lib/DirectAdminVacationSyncService.php b/exec/lib/DirectAdminVacationSyncService.php
new file mode 100644
index 0000000..07029cd
--- /dev/null
+++ b/exec/lib/DirectAdminVacationSyncService.php
@@ -0,0 +1,106 @@
+<?php
+declare(strict_types=1);
+
+final class DirectAdminVacationSyncService
+{
+    public function __construct(
+        private RuleRepository $rules,
+        private DirectAdminSyncRepository $sync,
+        private MailboxDirectory $mailboxes,
+        private DirectAdminVacationApi $api
+    ) {
+    }
+
+    public function syncUser(string $username): void
+    {
+        $rules = $this->rulesById($username);
+        foreach ($this->sync->allRuleEntries($username) as $ruleId => $entries) {
+            if (!isset($rules[$ruleId]) || empty($rules[$ruleId]['enabled'])) {
+                $this->deleteEntries($username, $ruleId, $entries);
+            }
+        }
+
+        foreach ($rules as $ruleId => $rule) {
+            if (empty($rule['enabled'])) {
+                continue;
+            }
+            $this->syncRule($username, $ruleId, $rule);
+        }
+    }
+
+    /** @return array<string,array<string,mixed>> */
+    private function rulesById(string $username): array
+    {
+        $out = [];
+        foreach ($this->rules->all($username) as $rule) {
+            $id = (string)($rule['id'] ?? '');
+            if ($id !== '') {
+                $out[$id] = $rule;
+            }
+        }
+        return $out;
+    }
+
+    /** @param array<string,mixed> $rule */
+    private function syncRule(string $username, string $ruleId, array $rule): void
+    {
+        $existing = $this->indexedEntries($this->sync->entriesForRule($username, $ruleId));
+        $targets = $this->targetMailboxes($username, $rule);
+        $next = [];
+        foreach ($targets as $mailbox) {
+            $email = strtolower((string)$mailbox['email']);
+            $this->api->saveVacation($username, $email, $rule, isset($existing[$email]));
+            $next[] = [
+                'rule_id' => $ruleId,
+                'domain' => (string)$mailbox['domain'],
+                'mailbox' => (string)$mailbox['mailbox'],
+                'email' => $email,
+                'api_key' => $email,
+                'last_sync_at' => time(),
+            ];
+            unset($existing[$email]);
+        }
+        foreach ($existing as $entry) {
+            $this->api->deleteVacation($username, (string)$entry['email']);
+        }
+        $this->sync->replaceRuleEntries($username, $ruleId, $next);
+    }
+
+    /** @param array<int,array<string,mixed>> $entries */
+    private function deleteEntries(string $username, string $ruleId, array $entries): void
+    {
+        foreach ($entries as $entry) {
+            $email = (string)($entry['email'] ?? $entry['api_key'] ?? '');
+            if ($email !== '') {
+                $this->api->deleteVacation($username, $email);
+            }
+        }
+        $this->sync->deleteRuleEntries($username, $ruleId);
+    }
+
+    /** @param array<int,array<string,mixed>> $entries @return array<string,array<string,mixed>> */
+    private function indexedEntries(array $entries): array
+    {
+        $out = [];
+        foreach ($entries as $entry) {
+            $email = strtolower((string)($entry['email'] ?? $entry['api_key'] ?? ''));
+            if ($email !== '') {
+                $out[$email] = $entry + ['email' => $email];
+            }
+        }
+        return $out;
+    }
+
+    /** @param array<string,mixed> $rule @return array<int,array{domain:string,mailbox:string,email:string}> */
+    private function targetMailboxes(string $username, array $rule): array
+    {
+        if (empty($rule['dynamic_scope']) && isset($rule['mailbox_snapshot']) && is_array($rule['mailbox_snapshot'])) {
+            return array_values(array_filter($rule['mailbox_snapshot'], static function (mixed $mailbox): bool {
+                return is_array($mailbox)
+                    && isset($mailbox['domain'], $mailbox['mailbox'], $mailbox['email'])
+                    && filter_var((string)$mailbox['email'], FILTER_VALIDATE_EMAIL);
+            }));
+        }
+        return $this->mailboxes->mailboxesForUser($username);
+    }
+}
diff --git a/plugin.conf b/plugin.conf
index 77b4107..97b479e 100644
--- a/plugin.conf
+++ b/plugin.conf
@@ -2,6 +2,7 @@ name=global-autoresponder
 id=global-autoresponder
 type=user
 author=HITME.PL
-version=1.0.5
+version=1.0.6
 active=no
 installed=no
+user_run_as=root
diff --git a/scripts/backend.sh b/scripts/backend.sh
index 075775c..730887b 100755
--- a/scripts/backend.sh
+++ b/scripts/backend.sh
@@ -3,6 +3,16 @@ set -eu
 
 BASE_DIR="/usr/local/hitme_plugins/global-autoresponders"
 STATE_FILE="$BASE_DIR/config/backend-state.json"
+PLUGIN_DIR="/usr/local/directadmin/plugins/global-autoresponder"
+CUSTOM_DIR="/usr/local/directadmin/custombuild/custom/exim"
+CUSTOM_CONF="$CUSTOM_DIR/exim.conf"
+SOURCE_CONF="/usr/local/directadmin/custombuild/configure/exim/exim.conf"
+ROUTER_SNIPPET="$PLUGIN_DIR/scripts/exim/global_autoresponder_router.conf"
+TRANSPORT_SNIPPET="$PLUGIN_DIR/scripts/exim/global_autoresponder_transport.conf"
+ROLLBACK_ACTIVE=0
+ROLLBACK_CREATED=0
+ROLLBACK_REBUILD=0
+ROLLBACK_FILE=
 
 usage() {
   echo "Usage: scripts/backend.sh da|exim" >&2
@@ -16,21 +26,161 @@ fi
 mkdir -p "$BASE_DIR/config" "$BASE_DIR/data" "$BASE_DIR/state" "$BASE_DIR/logs"
 chmod 700 "$BASE_DIR/config" "$BASE_DIR/logs"
 
+write_state() {
+  backend="$1"
+  printf '{"active_backend":"%s","migration_status":"complete"}\n' "$backend" > "$STATE_FILE"
+  chmod 600 "$STATE_FILE"
+}
+
+remove_marked_block() {
+  marker="$1"
+  file="$2"
+  tmp="${file}.global-autoresponder.$$"
+  awk -v marker="$marker" '
+    $0 == "# BEGIN global-autoresponder " marker { skip=1; next }
+    $0 == "# END global-autoresponder " marker { skip=0; next }
+    skip != 1 { print }
+  ' "$file" > "$tmp"
+  mv "$tmp" "$file"
+}
+
+insert_after_section() {
+  section="$1"
+  snippet="$2"
+  file="$3"
+  tmp="${file}.global-autoresponder.$$"
+  if ! awk -v section="$section" -v snippet="$snippet" '
+    BEGIN {
+      while ((getline line < snippet) > 0) {
+        block = block line "\n"
+      }
+      close(snippet)
+    }
+    { print }
+    $0 == section && inserted != 1 {
+      printf "\n%s\n", block
+      inserted = 1
+    }
+    END {
+      if (inserted != 1) {
+        exit 3
+      }
+    }
+  ' "$file" > "$tmp"; then
+    rm -f "$tmp"
+    echo "Cannot install exim backend: section $section not found in custom exim.conf." >&2
+    exit 1
+  fi
+  mv "$tmp" "$file"
+}
+
+backup_custom_conf() {
+  mkdir -p "$CUSTOM_DIR"
+  ROLLBACK_FILE="${CUSTOM_CONF}.global-autoresponder.backup.$$"
+  if [ -f "$CUSTOM_CONF" ]; then
+    cp "$CUSTOM_CONF" "$ROLLBACK_FILE"
+    ROLLBACK_CREATED=0
+  else
+    : > "$ROLLBACK_FILE"
+    ROLLBACK_CREATED=1
+  fi
+  ROLLBACK_ACTIVE=1
+}
+
+restore_custom_conf() {
+  if [ "$ROLLBACK_ACTIVE" != "1" ]; then
+    return
+  fi
+  set +e
+  if [ "$ROLLBACK_CREATED" = "1" ]; then
+    rm -f "$CUSTOM_CONF"
+  else
+    cp "$ROLLBACK_FILE" "$CUSTOM_CONF"
+  fi
+  rm -f "$ROLLBACK_FILE"
+  if [ "$ROLLBACK_REBUILD" = "1" ]; then
+    rebuild_and_reload_exim >/dev/null 2>&1
+  fi
+  ROLLBACK_ACTIVE=0
+}
+
+commit_custom_conf() {
+  rm -f "$ROLLBACK_FILE"
+  ROLLBACK_ACTIVE=0
+  ROLLBACK_CREATED=0
+  ROLLBACK_REBUILD=0
+}
+
+trap 'restore_custom_conf' EXIT
+trap 'restore_custom_conf; exit 1' HUP INT TERM
+
+validate_exim_conf() {
+  if command -v exim >/dev/null 2>&1; then
+    exim -C "$CUSTOM_CONF" -bV >/dev/null
+  elif command -v exim4 >/dev/null 2>&1; then
+    exim4 -C "$CUSTOM_CONF" -bV >/dev/null
+  else
+    echo "Cannot validate exim backend: exim binary not found." >&2
+    exit 1
+  fi
+}
+
+rebuild_and_reload_exim() {
+  if command -v da >/dev/null 2>&1; then
+    da build exim_conf
+  elif [ -x /usr/local/directadmin/custombuild/build ]; then
+    /usr/local/directadmin/custombuild/build exim_conf
+  else
+    echo "Cannot rebuild exim configuration: da/build command not found." >&2
+    exit 1
+  fi
+  if command -v systemctl >/dev/null 2>&1; then
+    systemctl reload exim 2>/dev/null || systemctl restart exim
+  else
+    service exim reload 2>/dev/null || service exim restart
+  fi
+}
+
 if [ "$1" = "da" ]; then
-  cat > "$STATE_FILE" <<'EOF'
-{"active_backend":"da","migration_status":"complete"}
-EOF
+  if [ -f "$CUSTOM_CONF" ]; then
+    backup_custom_conf
+    remove_marked_block "router" "$CUSTOM_CONF"
+    remove_marked_block "transport" "$CUSTOM_CONF"
+    if grep -Fq "global_autoresponder_" "$CUSTOM_CONF"; then
+      echo "Cannot switch to da: plugin Exim markers were not removed cleanly." >&2
+      exit 1
+    fi
+    validate_exim_conf
+    ROLLBACK_REBUILD=1
+    rebuild_and_reload_exim
+    commit_custom_conf
+  fi
+  write_state "da"
   echo "Backend set to da"
   exit 0
 fi
 
-CUSTOM_DIR="/usr/local/directadmin/custombuild/custom/exim"
-if [ ! -d "$CUSTOM_DIR" ]; then
-  echo "Cannot enable exim backend: safe CustomBuild exim customization directory not found." >&2
+if [ ! -d "$(dirname "$SOURCE_CONF")" ]; then
+  echo "Cannot enable exim backend: DirectAdmin CustomBuild exim source config not found." >&2
+  exit 1
+fi
+if [ ! -f "$ROUTER_SNIPPET" ] || [ ! -f "$TRANSPORT_SNIPPET" ]; then
+  echo "Cannot enable exim backend: plugin Exim snippets are missing." >&2
   exit 1
 fi
 
-cat > "$STATE_FILE" <<'EOF'
-{"active_backend":"exim","migration_status":"pending_exim_validation"}
-EOF
-echo "Backend prepared for exim; validate Exim customization before production use."
+backup_custom_conf
+if [ ! -f "$CUSTOM_CONF" ]; then
+  cp "$SOURCE_CONF" "$CUSTOM_CONF"
+fi
+
+remove_marked_block "router" "$CUSTOM_CONF"
+remove_marked_block "transport" "$CUSTOM_CONF"
+insert_after_section "begin routers" "$ROUTER_SNIPPET" "$CUSTOM_CONF"
+insert_after_section "begin transports" "$TRANSPORT_SNIPPET" "$CUSTOM_CONF"
+validate_exim_conf
+ROLLBACK_REBUILD=1
+rebuild_and_reload_exim
+commit_custom_conf
+write_state "exim"
+echo "Backend set to exim"
diff --git a/scripts/exim/global_autoresponder_router.conf b/scripts/exim/global_autoresponder_router.conf
index 5d60379..1bb7347 100644
--- a/scripts/exim/global_autoresponder_router.conf
+++ b/scripts/exim/global_autoresponder_router.conf
@@ -1,2 +1,11 @@
-# global-autoresponder router placeholder
-# This file must only be installed through DirectAdmin/CustomBuild-safe Exim customization paths.
+# BEGIN global-autoresponder router
+# Runs an unseen delivery to the plugin worker for local recipients. Normal mailbox
+# delivery continues because unseen is enabled and the worker suppresses ineligible mail.
+global_autoresponder_router:
+  driver = accept
+  domains = +local_domains
+  condition = ${if exists{/usr/local/directadmin/plugins/global-autoresponder/scripts/global_autoresponder_worker.php}{yes}{no}}
+  transport = global_autoresponder_transport
+  unseen
+  no_verify
+# END global-autoresponder router
diff --git a/scripts/exim/global_autoresponder_transport.conf b/scripts/exim/global_autoresponder_transport.conf
index 4adc9ff..9cc3144 100644
--- a/scripts/exim/global_autoresponder_transport.conf
+++ b/scripts/exim/global_autoresponder_transport.conf
@@ -1,2 +1,13 @@
-# global-autoresponder transport placeholder
-# This file must only be installed through DirectAdmin/CustomBuild-safe Exim customization paths.
+# BEGIN global-autoresponder transport
+# The worker receives the original message on stdin and Exim-provided envelope
+# variables such as SENDER, RECIPIENT, LOCAL_PART, and DOMAIN in the environment.
+global_autoresponder_transport:
+  driver = pipe
+  command = /usr/local/directadmin/plugins/global-autoresponder/scripts/global_autoresponder_worker.php
+  user = root
+  group = root
+  return_fail_output = false
+  log_output = true
+  message_prefix =
+  message_suffix =
+# END global-autoresponder transport
diff --git a/scripts/global_autoresponder_worker.php b/scripts/global_autoresponder_worker.php
index 278be5c..95b60dd 100755
--- a/scripts/global_autoresponder_worker.php
+++ b/scripts/global_autoresponder_worker.php
@@ -48,6 +48,9 @@ final class GlobalAutoresponderWorker
             if (!$this->isActiveRule($rule)) {
                 continue;
             }
+            if (!$this->ruleIncludesRecipient($rule, $recipient)) {
+                continue;
+            }
             $ruleId = (string)($rule['id'] ?? '');
             if ($ruleId === '') {
                 continue;
@@ -81,6 +84,24 @@ final class GlobalAutoresponderWorker
         return (int)($rule['start_ts'] ?? 0) <= $now && (int)($rule['end_ts'] ?? 0) >= $now;
     }
 
+    /** @param array<string,mixed> $rule */
+    private function ruleIncludesRecipient(array $rule, string $recipient): bool
+    {
+        if (!array_key_exists('dynamic_scope', $rule) || !empty($rule['dynamic_scope'])) {
+            return true;
+        }
+        $snapshot = $rule['mailbox_snapshot'] ?? [];
+        if (!is_array($snapshot)) {
+            return false;
+        }
+        foreach ($snapshot as $mailbox) {
+            if (is_array($mailbox) && strtolower((string)($mailbox['email'] ?? '')) === strtolower($recipient)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     /** @param array<string,string> $env @param string[] $keys */
     private static function firstEnv(array $env, array $keys): string
     {
diff --git a/scripts/sync_directadmin_vacations.php b/scripts/sync_directadmin_vacations.php
index f205e99..d950d5a 100755
--- a/scripts/sync_directadmin_vacations.php
+++ b/scripts/sync_directadmin_vacations.php
@@ -2,4 +2,81 @@
 <?php
 declare(strict_types=1);
 
-echo "DirectAdmin vacation synchronization is executed by plugin handlers when DA backend is active.\n";
+define('PLUGIN_ROOT', dirname(__DIR__));
+define('PLUGIN_EXEC_DIR', PLUGIN_ROOT . '/exec');
+
+foreach ([
+    'Settings.php',
+    'RuleRepository.php',
+    'DirectAdminSyncRepository.php',
+    'MailboxDirectory.php',
+    'DirectAdminVacationApi.php',
+    'DirectAdminVacationSyncService.php',
+] as $file) {
+    require_once PLUGIN_EXEC_DIR . '/lib/' . $file;
+}
+
+function sync_usage(): void
+{
+    fwrite(STDERR, "Usage: sync_directadmin_vacations.php [--user=USERNAME]\n");
+}
+
+try {
+    $targetUser = '';
+    foreach (array_slice($_SERVER['argv'] ?? [], 1) as $arg) {
+        if (str_starts_with($arg, '--user=')) {
+            $targetUser = substr($arg, 7);
+            continue;
+        }
+        sync_usage();
+        exit(2);
+    }
+    if ($targetUser === '') {
+        $targetUser = getenv('USERNAME') ?: getenv('USER') ?: '';
+    }
+    if ($targetUser !== '' && !preg_match('/^[A-Za-z0-9._-]+$/', $targetUser)) {
+        throw new InvalidArgumentException('Invalid username');
+    }
+
+    $settings = Settings::load(Settings::EXTERNAL_SETTINGS);
+    if ($settings->backendMode() !== 'da') {
+        echo "DirectAdmin backend is not active; nothing to sync.\n";
+        exit(0);
+    }
+
+    $users = $targetUser !== '' ? [$targetUser] : users_with_rules(Settings::DATA_DIR);
+    $service = new DirectAdminVacationSyncService(
+        new RuleRepository(),
+        new DirectAdminSyncRepository(),
+        new MailboxDirectory(),
+        new DirectAdminVacationApi()
+    );
+    foreach ($users as $username) {
+        $service->syncUser($username);
+        echo "Synced {$username}\n";
+    }
+    exit(0);
+} catch (Throwable $e) {
+    fwrite(STDERR, "DirectAdmin vacation synchronization failed: " . $e->getMessage() . "\n");
+    exit(1);
+}
+
+/** @return string[] */
+function users_with_rules(string $baseDir): array
+{
+    $dir = rtrim($baseDir, '/') . '/users';
+    if (!is_dir($dir)) {
+        return [];
+    }
+    $users = [];
+    foreach (scandir($dir) ?: [] as $entry) {
+        if ($entry === '.' || $entry === '..' || !preg_match('/^[A-Za-z0-9._-]+$/', $entry)) {
+            continue;
+        }
+        if (is_file($dir . '/' . $entry . '/rules.json')) {
+            $users[] = $entry;
+        }
+    }
+    sort($users);
+    return $users;
+}
diff --git a/tests/directadmin_vacation_sync_service_test.php b/tests/directadmin_vacation_sync_service_test.php
new file mode 100644
index 0000000..140da85
--- /dev/null
+++ b/tests/directadmin_vacation_sync_service_test.php
@@ -0,0 +1,96 @@
+<?php
+declare(strict_types=1);
+
+require_once PLUGIN_ROOT . '/exec/lib/Settings.php';
+require_once PLUGIN_ROOT . '/exec/lib/RuleRepository.php';
+require_once PLUGIN_ROOT . '/exec/lib/DirectAdminSyncRepository.php';
+require_once PLUGIN_ROOT . '/exec/lib/MailboxDirectory.php';
+require_once PLUGIN_ROOT . '/exec/lib/DirectAdminVacationApi.php';
+require_once PLUGIN_ROOT . '/exec/lib/DirectAdminVacationSyncService.php';
+
+test('directadmin vacation sync creates tracked entries for enabled rule mailboxes', function (): void {
+    $virtualRoot = TEST_TMP . '/da-sync-virtual';
+    test_write($virtualRoot . '/domainowners', "example.com: alice\n");
+    test_write($virtualRoot . '/example.com/passwd', "info:x:1000:12::/home/alice/imap/example.com/info:/bin/false\nsales:x:1000:12::/home/alice/imap/example.com/sales:/bin/false\n");
+
+    $repo = new RuleRepository(TEST_TMP . '/da-sync-data');
+    $rule = $repo->create('alice', [
+        'subject' => 'Urlop',
+        'body' => 'Body',
+        'start_value' => '2026-06-10|morning',
+        'end_value' => '2026-06-24|evening',
+        'start_ts' => 1,
+        'end_ts' => 2,
+        'enabled' => true,
+        'dynamic_scope' => true,
+    ]);
+
+    $calls = [];
+    $api = new class($calls) extends DirectAdminVacationApi {
+        public function __construct(private array &$calls) {}
+        public function saveVacation(string $owner, string $email, array $rule, bool $exists): void
+        {
+            $this->calls[] = ['save', $owner, $email, $exists, $rule['subject']];
+        }
+        public function deleteVacation(string $owner, string $email): void
+        {
+            $this->calls[] = ['delete', $owner, $email];
+        }
+    };
+
+    $sync = new DirectAdminVacationSyncService(
+        $repo,
+        new DirectAdminSyncRepository(TEST_TMP . '/da-sync-data'),
+        new MailboxDirectory($virtualRoot),
+        $api
+    );
+    $sync->syncUser('alice');
+
+    assert_same([
+        ['save', 'alice', 'info@example.com', false, 'Urlop'],
+        ['save', 'alice', 'sales@example.com', false, 'Urlop'],
+    ], $calls);
+
+    $tracked = (new DirectAdminSyncRepository(TEST_TMP . '/da-sync-data'))->entriesForRule('alice', (string)$rule['id']);
+    assert_same(['info@example.com', 'sales@example.com'], array_column($tracked, 'email'));
+});
+
+test('directadmin vacation sync deletes stale tracked entries after rule removal', function (): void {
+    $virtualRoot = TEST_TMP . '/da-sync-delete-virtual';
+    test_write($virtualRoot . '/domainowners', "example.com: alice\n");
+    test_write($virtualRoot . '/example.com/passwd', "info:x:1000:12::/home/alice/imap/example.com/info:/bin/false\n");
+
+    $dataDir = TEST_TMP . '/da-sync-delete-data';
+    $repo = new RuleRepository($dataDir);
+    $syncRepo = new DirectAdminSyncRepository($dataDir);
+    $rule = $repo->create('alice', [
+        'subject' => 'Urlop',
+        'body' => 'Body',
+        'start_value' => '2026-06-10|morning',
+        'end_value' => '2026-06-24|evening',
+        'start_ts' => 1,
+        'end_ts' => 2,
+        'enabled' => true,
+        'dynamic_scope' => true,
+    ]);
+    $syncRepo->replaceRuleEntries('alice', (string)$rule['id'], [
+        ['email' => 'info@example.com', 'domain' => 'example.com', 'mailbox' => 'info', 'api_key' => 'info@example.com'],
+    ]);
+    $repo->delete('alice', (string)$rule['id']);
+
+    $calls = [];
+    $api = new class($calls) extends DirectAdminVacationApi {
+        public function __construct(private array &$calls) {}
+        public function saveVacation(string $owner, string $email, array $rule, bool $exists): void {}
+        public function deleteVacation(string $owner, string $email): void
+        {
+            $this->calls[] = ['delete', $owner, $email];
+        }
+    };
+
+    $sync = new DirectAdminVacationSyncService($repo, $syncRepo, new MailboxDirectory($virtualRoot), $api);
+    $sync->syncUser('alice');
+
+    assert_same([['delete', 'alice', 'info@example.com']], $calls);
+    assert_same([], $syncRepo->entriesForRule('alice', (string)$rule['id']));
+});
diff --git a/tests/exim_worker_test.php b/tests/exim_worker_test.php
index 520921d..d2bb632 100644
--- a/tests/exim_worker_test.php
+++ b/tests/exim_worker_test.php
@@ -96,3 +96,49 @@ test('exim worker suppresses automated messages and ignores unresolved recipient
     ));
     assert_same(0, $sent);
 });
+
+test('exim worker respects static mailbox snapshot scope', function (): void {
+    $settingsPath = TEST_TMP . '/worker-snapshot-settings.conf';
+    test_write($settingsPath, "GLOBAL_AUTORESPONDER_BACKEND=exim\nGLOBAL_AUTORESPONDER_REPLY_EVERY_MESSAGE=true\n");
+    $settings = Settings::load($settingsPath);
+
+    $virtualRoot = TEST_TMP . '/worker-snapshot-virtual';
+    test_write($virtualRoot . '/domainowners', "example.com: alice\n");
+    test_write($virtualRoot . '/example.com/passwd', "info:x:1000:12::/home/alice/imap/example.com/info:/bin/false\nsales:x:1000:12::/home/alice/imap/example.com/sales:/bin/false\n");
+
+    $repo = new RuleRepository(TEST_TMP . '/worker-snapshot-data');
+    $repo->create('alice', [
+        'subject' => 'Urlop',
+        'body' => 'Body',
+        'start_ts' => 1,
+        'end_ts' => 2000,
+        'enabled' => true,
+        'dynamic_scope' => false,
+        'mailbox_snapshot' => [
+            ['domain' => 'example.com', 'mailbox' => 'info', 'email' => 'info@example.com'],
+        ],
+    ]);
+
+    $sent = 0;
+    $worker = new GlobalAutoresponderWorker(
+        $settings,
+        $repo,
+        new MailboxDirectory($virtualRoot),
+        new RepeatState(TEST_TMP . '/worker-snapshot-state', 1000),
+        static function () use (&$sent): bool {
+            $sent++;
+            return true;
+        },
+        1000
+    );
+
+    assert_same(0, $worker->handle(
+        ['SENDER_ADDRESS' => 'person@example.net', 'RECIPIENT' => 'sales@example.com'],
+        "Auto-Submitted: no\n\nBody"
+    ));
+    assert_same(1, $worker->handle(
+        ['SENDER_ADDRESS' => 'person@example.net', 'RECIPIENT' => 'info@example.com'],
+        "Auto-Submitted: no\n\nBody"
+    ));
+    assert_same(1, $sent);
+});
diff --git a/tests/handler_test.php b/tests/handler_test.php
index 11ae277..9cb7cf7 100644
--- a/tests/handler_test.php
+++ b/tests/handler_test.php
@@ -76,3 +76,39 @@ test('rule form uses native period selector in da mode', function (): void {
     assert_contains('Rano', $html);
     assert_false(strpos($html, 'type="time"') !== false);
 });
+
+test('mutating handlers synchronize active backend after storage changes', function (): void {
+    foreach (['create.php', 'update.php', 'delete.php', 'toggle.php'] as $handler) {
+        $source = file_get_contents(PLUGIN_ROOT . '/exec/handlers/' . $handler) ?: '';
+        assert_contains('syncActiveBackend', $source, $handler . ' must synchronize backend after mutation');
+    }
+});
+
+test('calendar picker is based on selected rule month and supports month navigation', function (): void {
+    $settingsPath = TEST_TMP . '/form-calendar.conf';
+    test_write($settingsPath, "DEFAULT_PLUGIN_LANGUAGE=pl\nGLOBAL_AUTORESPONDER_BACKEND=exim\n");
+    $settings = Settings::load($settingsPath);
+    $ctx = new AppContext(
+        new DirectAdminUser('alice', 'enhanced', 'pl', TEST_TMP . '/config'),
+        $settings,
+        new RuleRepository(TEST_TMP . '/data'),
+        new CsrfGuard('secret', 'alice', 'sid'),
+        Lang::load('pl', $settings),
+        new AuditLog(TEST_TMP . '/audit.log')
+    );
+
+    $html = render_rule_form($ctx, 'update', [
+        'id' => 'abc',
+        'subject' => 'Urlop',
+        'body' => 'Body',
+        'enabled' => true,
+        'start_value' => '2027-02-14T20:00',
+        'end_value' => '2027-03-01T09:30',
+    ]);
+
+    assert_contains('data-calendar-picker', $html);
+    assert_contains('data-calendar-prev', $html);
+    assert_contains('data-calendar-next', $html);
+    assert_contains('Luty 2027', $html);
+    assert_false(strpos($html, 'Czerwiec 2026') !== false);
+});
diff --git a/tests/package_contents_test.php b/tests/package_contents_test.php
index a5a907f..7cda04f 100644
--- a/tests/package_contents_test.php
+++ b/tests/package_contents_test.php
@@ -7,3 +7,40 @@ test('packing guidelines exclude docs and allow later manual icon', function ():
     assert_contains('must not contain `docs/`', $packing);
     assert_contains('may be added later at `src/images/user_icon.svg`', $packing);
 });
+
+test('plugin metadata runs user level as root on directadmin 1.689 plus', function (): void {
+    $conf = file_get_contents(PLUGIN_ROOT . '/plugin.conf') ?: '';
+    assert_contains('type=user', $conf);
+    assert_contains('user_run_as=root', $conf);
+});
+
+test('shipped plugin files do not contain placeholders', function (): void {
+    $bad = [];
+    $root = new RecursiveDirectoryIterator(PLUGIN_ROOT, FilesystemIterator::SKIP_DOTS);
+    $it = new RecursiveIteratorIterator($root);
+    foreach ($it as $file) {
+        if (!$file->isFile()) {
+            continue;
+        }
+        $path = $file->getPathname();
+        $relative = substr($path, strlen(PLUGIN_ROOT) + 1);
+        if (str_starts_with($relative, '.git/') || str_starts_with($relative, 'tests/')) {
+            continue;
+        }
+        $content = file_get_contents($path) ?: '';
+        if (preg_match('/placeholder|TODO|FIXME|not implemented|pending_exim_validation|stub/i', $content)) {
+            $bad[] = $relative;
+        }
+    }
+    assert_same([], $bad);
+});
+
+test('backend script protects custom exim config with rollback and exact section insertion checks', function (): void {
+    $script = file_get_contents(PLUGIN_ROOT . '/scripts/backend.sh') ?: '';
+    assert_contains('backup_custom_conf()', $script);
+    assert_contains('restore_custom_conf()', $script);
+    assert_contains("trap 'restore_custom_conf' EXIT", $script);
+    assert_contains('ROLLBACK_REBUILD=1', $script);
+    assert_contains('if ! awk -v section="$section" -v snippet="$snippet"', $script);
+    assert_contains('if (inserted != 1)', $script);
+});