I had a case where a single destination SMTP MX server was denying my send
request from what appeared to be an IP range-based RBL blacklist. Nobody
elses MXs levered that blacklist, so I only had the one problem delivery.
I was able to mockup a gateway on another server of mine in another IP
block and I temporarily used 'smtproutes' to clear my queue for that
Q: What solutions are being used in the wild to deal with this kind of case?
I could see an 'smtproutes' file that uses a ":farm.of.hostnames.tld" in
order to send your outbound email through a farm of servers in diverse
netblocks, but that implies a bit more scale than I can offer/afford.
I don't believe there's any available logic that says something like
"after a message is SMTP-connect-refused XX times, please try alternate
send path via 'othersmtproutes'" That's probably more overhead than
value, but it occurred to me...
Feedback is most welcome. (Please let me know if this is more appropriate
for the qmail list than vpopmail.)