diff --git a/plugins/managesieve/managesieve.js b/plugins/managesieve/managesieve.js
index c9b43fa6227..12338b51b2c 100644
--- a/plugins/managesieve/managesieve.js
+++ b/plugins/managesieve/managesieve.js
@@ -1007,10 +1007,14 @@ rcube_webmail.prototype.managesieve_tip_register = function (tips) {
 
 // format time string
 function sieve_formattime(hour, minutes) {
-    var i, c, h, time = '', format = rcmail.env.time_format || 'H:i';
-
-    for (i = 0; i < format.length; i++) {
-        c = format.charAt(i);
+    let time = '';
+    const format = rcmail.env.time_format || 'H:i';
+
+    // Support all Time and Timezone related formatters from PHP
+    // https://www.php.net/manual/en/datetime.format.php
+    // Even if not all may make sense in this context
+    for (let i = 0; i < format.length; i++) {
+        const c = format.charAt(i);
         switch (c) {
             case 'a':
                 time += hour >= 12 ? 'pm' : 'am';
@@ -1022,8 +1026,7 @@ function sieve_formattime(hour, minutes) {
                 break;
             case 'g':
             case 'h':
-                h = hour == 0 ? 12 : hour > 12 ? hour - 12 : hour;
-                time += (c == 'h' && hour < 10 ? '0' : '') + hour;
+                time += (c === 'h' && hour < 10 ? '0' : '') + (hour % 12 === 0 ? 12 : hour % 12);
 
                 break;
             case 'G':
@@ -1040,6 +1043,30 @@ function sieve_formattime(hour, minutes) {
                 break;
             case 's':
                 time += '00';
+
+                break;
+            case 'u': // Microseconds
+                time += '000000';
+
+                break;
+            case 'v': // Milliseconds
+                time += '000';
+
+                break;
+            case 'e': // Timezone identifier
+            case 'I': // Whether the date is in daylight saving time
+            case 'O': // Difference to Greenwich time (GMT) without colon between hours and minutes
+            case 'P': // Difference to Greenwich time (GMT) with colon between hours and minutes
+            case 'p': // The same as P, but returns Z instead of +00:00
+            case 'T': // Timezone abbreviation, if known; otherwise the GMT offset
+            case 'Z': // Timezone offset in seconds. The offset for timezones west of UTC is always negative, and for those east of UTC is always positive.
+                time += rcmail.env.server_timezone_info[c];
+
+                break;
+            case 'U': // Unix Timestamp
+                time += Math.round((new Date()).valueOf() / 1000);
+
+                break;
             default:
                 time += c;
         }
diff --git a/plugins/managesieve/managesieve.php b/plugins/managesieve/managesieve.php
index 1e160b60f83..f57b1dc850e 100644
--- a/plugins/managesieve/managesieve.php
+++ b/plugins/managesieve/managesieve.php
@@ -95,6 +95,22 @@ public function init_ui()
         $sieve_action = strpos($this->rc->action, 'plugin.managesieve') === 0;
 
         if ($this->rc->task == 'mail' || $sieve_action) {
+            // Injection of Timezone information into the JS Frontend.
+            // All the specifiers may be included in $config['time_format']
+            // However not all are easily parseable in the JS world, especially
+            // when it comes to Timezone abbreviation
+            $tz = new DateTimeZone($this->rc->config->get('timezone'));
+            $dt = new DateTime('now', $tz);
+
+            $this->rc->output->set_env('server_timezone_info', [
+                'e' => $dt->format('e'),
+                'I' => $dt->format('I'),
+                'O' => $dt->format('O'),
+                'P' => $dt->format('P'),
+                'p' => version_compare(\PHP_VERSION, '8.0.0') >= 0 ? $dt->format('p') : $dt->format('P'),
+                'T' => $dt->format('T'),
+                'Z' => $dt->format('Z'),
+            ]);
             $this->include_script('managesieve.js');
         }