--- a/program/steps/mail/func.inc	Thu Oct 09 11:31:41 2025 -0400
+++ b/program/steps/mail/func.inc	Wed Oct 15 14:06:27 2025 -0400
@@ -890,17 +890,17 @@
     // initialize HTML washer
     $washer = new rcube_washtml($wash_opts);
 
-    if (!$p['skip_washer_form_callback']) {
+    if (empty($p['skip_washer_form_callback'])) {
         $washer->add_callback('form', 'rcmail_washtml_callback');
     }
 
     // allow CSS styles, will be sanitized by rcmail_washtml_callback()
-    if (!$p['skip_washer_style_callback']) {
+    if (empty($p['skip_washer_style_callback'])) {
         $washer->add_callback('style', 'rcmail_washtml_callback');
     }
 
     // modify HTML links to open a new window if clicked
-    if (!$p['skip_washer_link_callback']) {
+    if (empty($p['skip_washer_link_callback'])) {
         $washer->add_callback('a', 'rcmail_washtml_link_callback');
         $washer->add_callback('area', 'rcmail_washtml_link_callback');
 
@@ -1536,7 +1536,7 @@
         }
 
         // handle body styles related to background image
-        if ($style['background-image']) {
+        if (!empty($style['background-image'])) {
             // get body style
             if (preg_match('/#'.preg_quote($cont_id, '/').'\s+\{([^}]+)}/i', $body, $m)) {
                 // get background related style
@@ -1587,11 +1587,13 @@
         $end = ' />';
     }
     else if (preg_match('/^mailto:(.+)/i', $attrib['href'], $mailto)) {
-        list($mailto, $url) = explode('?', html_entity_decode($mailto[1], ENT_QUOTES, 'UTF-8'), 2);
+        $url_parts = explode('?', html_entity_decode($mailto[1], ENT_QUOTES, 'UTF-8'), 2);
+        $mailto    = $url_parts[0];
+        $url       = $url_parts[1] ?? '';
 
         // #6020: use raw encoding for correct "+" character handling as specified in RFC6068
-        $url       = rawurldecode($url);
-        $mailto    = rawurldecode($mailto);
+        $url       = rawurldecode($url??'');
+        $mailto    = rawurldecode($mailto??'');
         $addresses = rcube_mime::decode_address_list($mailto, null, true);
         $mailto    = array();
 
@@ -2050,7 +2052,7 @@
 
     $name = strtolower($name);
 
-    if ($alias = $map[$name]) {
+    if ($alias = ($map[$name]??null)) {
         $name = $alias;
     }
     // Some versions of Outlook create garbage Content-Type: