Rob wrote:
A vanilla qmail install will accept email for domains listed in rcpthosts. If no other instructions are specified in either virtualdomains or smtproutes, qmail should just follow the published MX and forward the email to the primary - which it does.
That isn't right. You should never add a domain to rcpthosts that isn't local without also adding a line to smtproutes, because otherwise you could easily trigger a mail loop. Qmail has no understanding of "primary" - once a message is queued it uses the normal MX lookup methodology, including failing over to higher distance MX records, which may be itself. Sure, qmail will eventually detect the mail loop (I can't remember how many hops) and fail the message, but if your "primary" server is unreachable, you will mailbomb yourself with looping messages (trust me, I've done it [accidentally]).
But with the qpsmtpd upgrade, the old qmail behavior doesn't seem to be the case.
Add a smtpdroute record and you should be fine (this is precisely how my old company's servers are configured).
John
