There are just more and more screwed up mail servers out there and we are spending more and more time tracing emails and debugging other peoples services to prove to our customers we are not screwing up.
I've written about this in the past, but now it is a daily occurance we are having to do this.
It seems there are just more and more idiots out there setting up stupid "clever" configuration. Some idiots just configure their mail server without the .com on their domain and then ask us why there are prrblems? Every day it is the for the past 2 weeks it has been the same.
I'm guessing the ratio of domains/systems to trained engineers is getting out of whack. Some more and more fuck-wits are becoming in charge of mail servers and "improve things".
Anyway either the economics of email are going to have to be adjusted or I think email will become less used due to reliability.
If you are setting mail server, don't touch the config, the retries, the queue's, don't do anything clever, input your domain and that's it.