Sometime ago I built a web app that automatically emails an image that is proof of their advertising purchase. The system has a short message about this being their proof for their advertisement,, etc etc.. In the email I specify the reply address as being an address in our core domain while the email is actually sent via phpMail on our third party host from a domain NOT the same as the reply address I specify..
Everything works great, everybody receives their email with out issue EXCEPT for a couple entities.
I did take a look into the ip address being black listed and found one result.. BARRACUDA..
I am asking if anybody can give me some advice on the best rules of thumb for getting emails past filters (I know that is a loaded question) or any information about BARRACUDA, i.e. what their place is in the industry, what email programs use their service, etc...