[RichieBoy67]

ATT is very easy to get blacklisted from. Perhaps I didn't read this thread thoroughly enough because I thought your only blacklisting was spamheuisen?

You will have to jump through some hoops if blacklisted through att and chances are other services may do it as well. Bell south is another one that blacklists very easily.

You will most likely need an opt in and opt out link and send them privacy page links among other things. I am not sure if fixing the dns issues will be enough.

Temporarily you could add a note into your registration page to tell people that certain emails may be blocked and to use another email account.