finishing the postfix configuration

In an earlier post I'd written about the postfix configurations for virtual domain-based forwarding. Actual implementation had a few extra steps - needing some googling to remove two errors caught with

tail -f /var/log/mail/errors

One more mystery solved was why nmap was showing port 25 as closed - postfix was listening only on the loopback interface - localhost.

inet_interfaces = all

solved that.

First I thought just copying the main.cf from the older server was the reason. But even replacing it with the main.cf.dist with appropriate modifications didn't solve the problem.

The first one was

 fatal: connect #11 to subsystem private/proxymap: Connection refused

and the other, later, was

 fatal: connect #11 to subsystem private/scache: Connection refused

Deleting the proxymap socket (present in /var/spool/postfix/private ) only changed the error to file not found.
mksock gave file not found - the mksock util was not in the system at least with that name...
Finally adding

proxy_read_maps = $local_recipient_maps
local_recipient_maps = unix:passwd.byname

removed the first error and gave the second one. This one was finally removed by later adding

smtp_connection_cache_on_demand = no

One more thing I'd overlooked was the differing postfix versions needing different commands to update the alias database and the virtual database. This is actually mentioned in the small text at the bottom of the linuxquestions link in small print. Anyway, for the record, they are

postalias /etc/postfix/aliases

and

postmap /etc/postfix/virtual

respectively...