edit mailinglists

app/UI/Client/DistributionList/Providers/EditListDataProvider.php

@@ -193,7 +193,7 @@ class EditListDataProvider extends AddListDataProvider
             'SenderThisList' => $lang->absoluteT('SenderThisList')
         ];
 
-        $this->data['customMember'] = $extMembers;
+        $this->data['customMember'] = implode(',',$extMembers);
         $this->data['memberListActually'] = $intMembers;
         foreach($availableMembers as $availableMember) {
             $this->availableValues['memberListActually'][$availableMember] = $availableMember;