Running Postfix on Linux.
I know how to create IP aliases.
I know how to create multiple smtp transports and bind them to various IPs:
I know how to assign a transport to a specific recipient domain:
# cat transport yahoo.com yahoo: gmail.com gmail:
What I don't know is how to get Postfix to use multiple transports for a single recipient domain, each transport bound to a different IP. If that was possible, I could create several IP aliases, bind a transport to each, and spread delivery to a specific domain over all those aliases.
The reason I want to do this is that some ISPs are exceedingly slow to take in emails. 75% of our emails are delivered very quickly, but then there's this straggler ISP who has a lot of recipients but takes a very very long time on the intake because they are throttling everything down a lot, per sender IP.