Fix bug where inline images could have been ignored if Content-Id header contained redundant spaces (#6980)

CHANGELOG

@@ -2,6 +2,7 @@ CHANGELOG Roundcube Webmail
 ===========================
 
 - Fix permissions on some folders created by bin/install-jsdeps.sh script (#6930)
+- Fix bug where inline images could have been ignored if Content-Id header contained redundant spaces (#6980)
 
 RELEASE 1.3.10
 --------------

program/lib/Roundcube/rcube_imap.php

@@ -2135,8 +2135,7 @@ class rcube_imap extends rcube_storage
 
         // get part ID
         if (!empty($part[3])) {
-            $struct->content_id = $part[3];
-            $struct->headers['content-id'] = $part[3];
+            $struct->content_id = $struct->headers['content-id'] = trim($part[3]);
 
             if (empty($struct->disposition)) {
                 $struct->disposition = 'inline';