Transport based on headers

Martin

I am using mailcow dockerized and have the following situation.

If user x mails to user y on different domains and the subject contains secret it should be relayed. However this should never be done for local email.

Currently I use postfix smtp_check_headers for checking different subjects and the sensitivity header and using filter for the relay. But I’m stuck with the local delivery part. It seems I can’t stop the relaying for the same domain.

I was wondering how you would do this in mailcow? Maybe something else as postfix?

Martin

I have been looking into Dovecot Sieve, but this is only for incoming mail and i would need it for outgoing.

So i only see Postfix as an option for now, but still have not found an way to only do it for mails leaving the server.

These are some of my current smtp_header_checks:
/^Sensitivity: \s*(Company-Confidential)\s*$/ FILTER smtp:[1.1.1.1]:25 /^Subject: (.*)secure(.*)/ FILTER smtp:[1.1.1.1]:25

But this will also be applied for local delivery.