[freebsd-questions] slightly OT - my freebsd email topology

[Howard Jones]

Jonathan Horne wrote:
> currently, my email server is just a single box, accepting and sending emails
> from and to the internet.  spamassassin and sendmail, and so far, it works
> satisfactory.
>
> i would like to change it up, so that i have a pair of servers doing MX from the
> internet, which then passes to an internal server for delivery.  if i do that, i
> could remove spamassassin from the internal server, and run it on just the 2
> external.  all those configurations is really not my issue here... what im
> really pondering is how would external servers that are seperate from where the
> target mailboxes are, know which addressess are acceptable and which to return a
> 550?
>   
I did this for our backup MX using qpsmtpd and a plugin I wrote to check 
against an automatically updated file. qpsmtpd can deliver onwards to 
any SMTP server after running whatever filtering/fussiness you specify.

I believe there is a milter plugin that can do onward queries before 
accepting mail, too, although I don't use sendmail, so I couldn't tell 
you the name of it...