Fix To: header encoding in mail sent with mail() method (#5475)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix To: header encoding in mail sent with mail() method (#5475)
 - Fix flickering of header topline in min-mode (#5426)
 - Fix bug where folders list would scroll to top when clicking on subscription checkbox (#5447)
 - Fix decoding of GB2312/GBK text when iconv is not installed (#5448)

program/lib/Roundcube/rcube.php

@@ -1676,7 +1676,7 @@ class rcube
             }
             else {
                 $delim      = $this->config->header_delimiter();
-                $to         = $mailto;
+                $to         = $message->encodeHeader('To', $mailto, RCUBE_CHARSET, 'quoted-printable');
                 $subject    = $headers['Subject'];
                 $header_str = rtrim($header_str);