diff --git a/tls_icon.php b/tls_icon.php
index a6bbecc..2f8c3b5 100644
--- a/tls_icon.php
+++ b/tls_icon.php
@@ -5,6 +5,7 @@ class tls_icon extends rcube_plugin
 	const POSTFIX_TLS_REGEX = "/\(using (TLS.*)\) \(/im";
 	const POSTFIX_LOCAL_REGEX = "/\([a-zA-Z]*, from userid [0-9]*\)/im";
 	const SENDMAIL_TLS_REGEX = "/\(version=(TLS.*)\)(\s+for|;)/im";
+    const STALWART_TLS_REGEX = "/\(using (TLSv1\.[23] with cipher .+)\) by .+ \(Stalwart SMTP\)/im";
 
 	private $message_headers_done = false;
 	private $icon_img;
@@ -60,7 +61,8 @@ public function message_headers($p)
 			}
 
 			if (preg_match_all(tls_icon::POSTFIX_TLS_REGEX, $Received, $items, PREG_PATTERN_ORDER) ||
-				preg_match_all(tls_icon::SENDMAIL_TLS_REGEX, $Received, $items, PREG_PATTERN_ORDER)) {
+                preg_match_all(tls_icon::SENDMAIL_TLS_REGEX, $Received, $items, PREG_PATTERN_ORDER) ||
+				preg_match_all(tls_icon::STALWART_TLS_REGEX, $Received, $items, PREG_PATTERN_ORDER)) {
 				$data = $items[1][0];
 				$this->icon_img .= '<img class="lock_icon" src="plugins/tls_icon/lock.svg" title="' . htmlentities($data) . '" />';
 			} elseif (preg_match_all(tls_icon::POSTFIX_LOCAL_REGEX, $Received, $items, PREG_PATTERN_ORDER)) {