I think the only way to deal with that right now is to hire a company whose job is to deal with it. They'll random-check your outgoing emails are indeed what yo

I think the only way to deal with that right now is to hire a company whose job is to deal with it. They'll random-check your outgoing emails are indeed what you say they are, and they maintain a reputation with the big providers for checking it properly. What pre-validation could you do that would possibly be useful?