I don't know if it makes a difference, I don't have quotes on my mail_plugins: I don't have quotes too (It's difference between config file and dovecot -n output)
Did you check permissons on the replication fifos? For what? I think that problems on slave. How it should work in automatic mode? I repeat that from slave manually all works fine:
As I can see nothing happens automatically. But mx2:~# doveadm -D sync -u abuse@example.com -d -N -l 30 -Usuccessfully executed and getting mails from mx1.
prw-rw---- 1 dovecot mail 0 May 8 06:29 replication-notify-fifo
Does it work if you issue:
doveadm replicator replicate '*' mx1:~# doveadm replicator replicate '*' 2 users updated
doveadm replicator status '*' I already posted this output.
Do you have different hostnames for your servers? Sure. You may see in listing that short hostnames are mx1 and mx2.