I've been able to receive nearly 100% from the big guys. For folks that run their own I run into less issues these days. I'm still on Postfix. Some of the cli

I've been able to receive nearly 100% from the big guys. For folks that run their own I run into less issues these days. I'm still on Postfix. Some of the client and header checks used to (c2005) be too strict. But! When it failed, there were logs I could see. If you run your own, you'll want to get some log checking tools to make sure things are tidy.