[Dovecot] Fwd: sender address of sieve vacation script

Dear Odhiambo,

The <> represents the "null sender" in SMTP parlance. I think the
issue here is that the destination SMTP server does NOT accept the
null sender (<>), and that is a br0ken configuration. It has nothing
to do with Dovecot though. I am not good at interpreting postfix
logs so I cannot advise further.

100% correct answer. I checked with the admin of the relay and it´s working now. Thank you very much

Best regards, Wolfgang Burger