I have three email accounts set up on my computers. One is a .Mac Account, the other two use other email hosts. Since installing El Capitan I can not send mail via the non .Mac accounts. When I first launched 10.11 I had a message to confirm the email account passwords in the Internet Accounts Preference Panel which I have done, but still no success. The same accounts work perfectly on my MacBook which is still running OS X 10.10.5 Any suggestions?