Exchange - the User-Account you use to send from is not allowed to sent Mail from the account set for sending Mails

Em Client 6.0.21372.0

Server Exchange

The Account works fine. Only sending Mails Fails with the message:

Das Versenden der E-Mail ist fehlgeschlafen mit folgendem Fehler: Das Benutzerkonto, das zum Übermitteln dieser Anforderung verwendet wurde, ist nicht berechtigt, E-Mail im Auftrag des angegeben Kontos zu senden.

I have running a secong Acount with Kerio, there are no Problems …

I tried different Settings for User Account and for Account used sending Mails. Nothing works.

Maybe someone had an Idea?

Hi, this unfortunately points out to a server-setup issue, seems like the account you’ve used for sending the message does not have permission to send messages over the protocol or is only enabled for downloading messages. Please make sure this account has all permissions for sending messages, and check if the issue persists.

Thank you,
Paul