Thanks for helping!
Good find, for sure the ':' was missing.
I am surprised dovecot did not complain about the user names with a {plain} in them or that users did not have a password defined in the password file.
Now the query with doveadm works if I specify user1@site1.com.
I am still struggling with how postfix connects to dovecot.
I get these in the log: postfix/smtpd[]: warning: host or service srv_dovecot:12345 not found: Temporary failure in name resolution postfix/smtpd[]: warning: SASL: Connect to Dovecot auth socket 'inet:srv_dovecot:12345' failed: Cannot assign requested address postfix/smtpd[]: fatal: no SASL authentication mechanisms postfix/master[]: warning: process /usr/lib/postfix/sbin/smtpd pid 194 exit status 1 postfix/master[]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling
I am not sure why postfix complains that it cannot find srv_dovecot since I can ping it and open a telnet of the IP/Port from where Postfix is running: Tried manually and I can connect to the dovecot SASL port: # telnet srv_dovecot 12345 Trying <IP>... Connected to srv_dovecot. Escape character is '^]'. VERSION 1 2 MECH PLAIN plaintext SPID 2118 CUID 4 COOKIE 7dc4cf7b8765bc594ff0cf051d99e6ee DONE ^] telnet> quit
Another line I am not understanding: postfix_log/error[]: CDC9DA5535: to=postmaster@localdomain, orig_to=<postmaster>, relay=none, delay=139002, delays=139002/0.04/0/0.01, dsn=4.4.3, status=deferred (delivery temporarily suspended: Host or domain name not found. Name service error for name=localdomain type=MX: Host not found, try again)