> On Nov 22, 2018, at 4:32 AM, Stefan Bauer <cubew...@googlemail.com> wrote: > > Found it. Was required to modify smtp_auth to > > customer1.de user1:password > customer2.de user2:password.
Nope: http://www.postfix.org/SASL_README.html#client_sasl_sender Generally, with Postfix lookups by email address, the lookup key is either the full localpart@domain address, or an "@domain" wildcard, as e.g. with all address rewriting tables, ... The primary exceptions are access(5) lookups and transport(5) lookups, which use the bare domain. -- Viktor.