El Capitan Outgoing Mail server problems Just upgraded to El Capitan on my Mac mini. Mail has a problem though I have multiple mail accounts set-up 


The outgoing SMTP smtp server for all accounts is NONE
If I assign one from the drop list it tries to apply that selection to ALL accounts
The "Edit SMTP server list" option in the drop down box is now missing


I've deleted all the accounts (closed mail, restarted, re-opened mail) and added back 2 of them but all these issues still exist. 

Can't see anyone that has my issue although a lot seem to have the outgoing mail server issues. 

My Macbook Pro (older) upgrade did not have these problems (although a small issue with one account easily fixed) the "edit SMTP server List" options appears as it always did and different outgoing servers can be assigned to different mail accounts. 

Not sure what else to do??????
It seems that the solution is to delete all accounts (hoping you have no pop accounts) and recreate them, but not in Mail; go to System Preferences>Internet Acccounts to delete and recreate the accounts. When you recreate one, you have the choice to choose email account only (scroll down to Add another count (not sure of the english, I translate from french) and clic on it.
Of course, work with Mail closed.
The account you create there are created in Mail.When you finish to recreate all your accounts, reopen mail, et voilà!