Working now...
I enabled port 24 in dovecot on both proxy and backend (previously i was just telling postfix to listen to port 24 on the backend server) -- Confirmed lmtp on 24 was working on both servers by telnet localhost 24 (220 Dovecot LMTP ready response)
here are my settings
proxy is using inet for LMTP
dovecot/conf/10-master.conf service lmtp { unix_listener lmtp { #mode = 0666 }
# Create inet listener only if you can't use the above UNIX socket inet_listener lmtp { port = 24 } }
postfix/main.cf
virtual_transport = lmtp:localhost mailbox_transport = lmtp:localhost
backend is also inet (to receive) and unix socket (to deliver locally)
dovecot/conf/10-master.conf service lmtp { unix_listener lmtp { #mode = 0666 }
unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix # mode = 0660 user = postfix }
# Create inet listener only if you can't use the above UNIX socket inet_listener lmtp { port = 24 } }
postfix/main.cf virtual_transport = lmtp:unix:private/dovecot-lmtp mailbox_transport = lmtp:unix:private/dovecot-lmtp
postfix/master.cf removed: 24 inet n - n - - lmtp