[jesterson]

I've had similar case where our email was blocked by Symantec product, which happened to be used by email services a lot.

I've spent enormous amount of time communicating with providers and Symantec with little or no luck. Provider's stuff is incompetent and lazy quite often, they mostly didn't reply or replied with response we can't do so. Contacting Symantec wasn't helpful as well - they recommended to talk to email provider's stuff.

Eventually we set up mail routing for those domains via other server/domain - whichever worked in each case. It's tedious to maintain but there is no way around. Using well known email service is not a guarantee as well - some email services might block it for no reason or just use product which is blocking it.

Summarising, I'd focus on improving deliverability in any possible way without wasting time for communication.

[joshpangell]

Thanks for the advice