Split from this thread.

I just switched from Time Warner to AT&T and have the exact same problem with my work email (not Hotmail, not ATT mail) going through Windows Live Mail.  It was working just fine, and then suddenly the outgoing/sent mail won't work.  I have tried every server combination under the sun.  This has to be a compatibility issue with WLM and AT&T yet neither party seems to have an answer.  Really irritating.  It's 2014!!