diff --git a/CHANGELOG b/CHANGELOG
index 2a75a246e..fc502ae77 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -45,6 +45,7 @@ CHANGELOG Roundcube Webmail
 - Enigma: Fix bug where revoked users/keys were not greyed out in key info
 - Enigma: Fix error message when trying to encrypt with a revoked key (#6607)
 - Enigma: Fix "decryption oracle" bug [CVE-2019-10740] (#6638)
+- Enigma: Fix bug where signature verification could have been skipped for some message structures (#6838)
 - Fix css styles leak from replied/forwarded message to the rest of the composed text (#6831)
 - Fix invalid path to "add contact" icon when using assets_path setting
 - Fix invalid path to blocked.gif when using assets_path setting (#6752)
diff --git a/program/lib/Roundcube/rcube_imap.php b/program/lib/Roundcube/rcube_imap.php
index e5ac6e274..3b408e99c 100644
--- a/program/lib/Roundcube/rcube_imap.php
+++ b/program/lib/Roundcube/rcube_imap.php
@@ -2406,13 +2406,15 @@ class rcube_imap extends rcube_storage
             $part_data = rcube_imap_generic::getStructurePartData($structure, $part);
 
             $o_part = new rcube_message_part;
-            $o_part->ctype_primary = $part_data['type'];
-            $o_part->encoding      = $part_data['encoding'];
-            $o_part->charset       = $part_data['charset'];
-            $o_part->size          = $part_data['size'];
+            $o_part->ctype_primary   = $part_data['type'];
+            $o_part->ctype_secondary = $part_data['subtype'];
+            $o_part->encoding        = $part_data['encoding'];
+            $o_part->charset         = $part_data['charset'];
+            $o_part->size            = $part_data['size'];
         }
 
-        if ($o_part && $o_part->size) {
+        // Note: multipart/* parts will have size=0, we don't want to ignore them
+        if ($o_part && ($o_part->size || $o_part->ctype_primary == 'multipart')) {
             $formatted = $formatted && $o_part->ctype_primary == 'text';
             $body = $this->conn->handlePartBody($this->folder, $uid, true,
                 $part ? $part : 'TEXT', $o_part->encoding, $print, $fp, $formatted, $max_bytes);
diff --git a/program/lib/Roundcube/rcube_imap_generic.php b/program/lib/Roundcube/rcube_imap_generic.php
index 3fe3f7b62..5ff525407 100644
--- a/program/lib/Roundcube/rcube_imap_generic.php
+++ b/program/lib/Roundcube/rcube_imap_generic.php
@@ -3634,6 +3634,7 @@ class rcube_imap_generic
         }
         else {
             $data['type']     = strtolower($part_a[0]);
+            $data['subtype']  = strtolower($part_a[1]);
             $data['encoding'] = strtolower($part_a[5]);
 
             // charset