Adding email to IOS Mail failing

I had 3 emails coming into my Iphone 6.   One stopped working about a week ago.  I was told to delete the failing account and re-add it.  It keeps getting failures and will not re-add.  I have talked to both mobility support and Att support and neither was able to fix it.  I get emails from this account on outlook and I can log into yahoo to see these emails.  This tells me my email address and my password are both fine.   The other two emails on my Iphone continue to work fine  I use POP, inbound.att.net and outbound.att.net   Incoming port is 995 and outgoing 465   I have tried adding other email addresses and they also fail  My email is [email scrubbed] (xxx replaces actual name)    I have one ATT account and the other addresses are sub accounts