I use Apple Mail on Yosemite 10.10.3 and my portal is AT&T. It seems that whenever I get a new email sub-account with AT&T Apple mail somehow screws it up so that I cannot get the new accounts to connect. OK, took the wild chance that I may have screwed up and went and changed all my passwords on ATT and Mail. Everything worked and the changes were acknowledged on ATT. Not mail. I have 6 new sub-accounts and a main account that mail is constantly jumping up and down to have passwords entered so it can connect. I have done so at least 8 times and it still won't connect. I used the ATT diagnostic tool and it said the internet connection is fine. So, I'm at a loss as to what to do. Shall I delete all the accounts on Mail and reenter them with the passwords or is it a localhost issue or am I missing something. This is not the first time that this has happened and I worked with ATT for over an hour to straighten it out with them and they said it was a problem inherent in Apple Mail. To be clear I had to change nothing at ATT to get the first one straightened out. It was all Apple Mail so I am looking at how to avoid this in the future as Apple Mail is the default mail for the Mac. Thanks.