Mail Sierra Outgoing Server Missing

Aloha,

I recently found out that I could not send outgoing mail, I get the error "no preferred outgoing server for this account".

I had this problem on El Capitan and it affected all email accounts. So I upgraded to Sierra hoping that it would be corrected on the upgrade (I know should have done this before but my iMac is for 2011 and I didn't want to slow it down anymore with the new software - but that is another story).

Anyway after the upgrade my iCloud and Gmail outgoing servers are listed but not the ones for my 1and1.com hosted accounts.

I eventually decided that I need to add the outgoing servers manually so I got the needed information from 1and1 and tried to update the server list. I can add the server to the SMTP list but when I go to add the server to the account the new server "disappears'. What I mean is that I can choose it but after several seconds, it goes back to "None" as the outgoing server.

I can access the email from the web interface so it is not a problem other than having to of on the web to send messages.

I have no problem receiving, I use the Connection Doctor to check and I have received incoming email.

What's my next step? Delete accounts and then add them?

Mahalo.