My small office client upgraded his internet connection and I've updated the
self hosted postfix configuration file with the new IP address.
Soon after, email users began complaining about bounces they started receiving
for some emails they sent.
After examining logs I've concluded that the newly IP was reused from another
client and it is listed in few rbl. One server did not even let me say HELO,
just printing a 5xx message and closing tcp connection.
I've reverted the change to ensure email continuitiy (as the old connection is
still available) and waiting for rbl to expire, and also asked ISP to create a
dns PTR record for it (it didn't have one).
But until these will be solved I'd like to instruct postfix to retry a 5xx
response using the secondary IP (so the smtp client to try connecting using the
new outbound source IP, and if gets a 4xx or 5xx to try again using the good
old clean IP).
Is this possible?
Using an old version (2.9.6) on Debian Wheezy 32bit.