Forwarded EMail rejected by Strato since short

UCS - Univention Corporate Server
#1

Hi,
since some time, Strato rejects mails, coming from itself (...@news.strato.de), which are forwarded to an external mail address. Return message is:

Letzter Fehler: 550 5.7.1
Erklärung: Unerlaubte Domain ‘news.strato.de’ im Envelope-From (B-EFROM-STRATO)
English: Unauthorized Domain ‘news.strato.de’ in Envelope-From (B-EFROM-STRATO)
Siehe
https://www.strato.de/faq/mail/fehlermeldungen-bei-e-mails

I do not know how to face this - so let me explain my setup:

  • I have UCS installed with Kopano
  • The User has in UCS Admin Console User Advanced Settings Category unden EMail forwarding an external address configured to forward to.
  • That works for internal mail, aswell as mail received from external sources, apart from strato’s own domains as sender addresses. It worked until maybe June / July, but stopped since.
  • I use fetchmail to fetch my mailboxes (which are hosted by Strato), and fetchmail delivers them to the UCS postfix
  • postfix delivers either locally or via Strato smtp relay
  • Its when the forwarded mail is received by the relay that I get a mail with the error message back.

I see two options:

  1. prevent all forwarding of mails from strato to the external account (not prefered)
  2. ensure that another Envelop-From is used when delivered to the relay, maybe onyl for mails from strato.

Neither one I know how to configure. For the second I’m even not sure which Envelop-From is used. The forwarded message contains an X-Envelope-From: return@news.strato.de - is it this one? Or how is Envelop-From setup in a forwarding case?

Anyone has some ideas how to tackle this?

Thanx
Joja

#2

@jst Did you find a solution for that issue. We are facing the same issue with mail distribution groups. Most recipients will just bounce those mails since the sender domain does not equal the mail domain of our UCS server. I think this has to do with SPF which gets implemented more and more.

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