[technion]

I was in a very similar position and found all my email bounced by every Cisco Ironport user. Contacting Cisco gave me the usual "please stop sending spam" sort of answer.

I then had a customer who actually had a Cisco support agreement log a case, and was promptly informed that I needed to create an account on abuse.net and register our domain to resolve the issue. I did, and it immediately resolved the issue.

It's a frustrating, terrible situation, where you follow every possible best practice you can find, and you're at the mercy of a third party you've never heard of. I get that RBLs are a similar situation, but you can usually identify when that's a cause.

I've had this recur over the years with 5-6 other domains, but there doesn't seem to be any pattern to it, it certainly isn't an issue with every domain.