I have a server which will try to send mails directly to destination MX servers. But some of them are rejecting the mails due to MTA's poor reputations(thats what they say).
I did every thing to improve reputation, and have no option left.
Only a couple of servers are rejecting our mails. So I thought to use Postmark for sending such mails.
But I need to configure Postfix to use sasl auth only for
fallback_relay and not for direct mails to MX server.
Some MX servers are giving error due to this sasl authentication(like hotmail). Google servers are accepting without problem.
#my configuration smtp_sasl_auth_enable = yes smtp_sasl_password_maps = static:key:key smtp_sasl_security_options = noanonymous fallback_relay = [smtp.postmarkapp.com]:25