I am able to receive email, but I am not able to send email. I have run the Connection doctor - My email connects to the internet; I connect to the incoming mail server (mail.mac.com), but I am not able to connect to the Outgoing Mail Server (smtp.mac.com). Any suggestions?
In connection doctor double click on your smtp server and click on Advanced.
Set the port to 587, authentication to password and make sure your user name and password are entered, the click OK.
Click the window close button and select Save.
Test
In connection doctor double click on your incoming mail server that is red.
Click on Advanced and put a checkmark in SSL and the port should change to 993 if .mac or imap or port 995 for pop.
If it does not then uncheck the box and recheck it.
This is assuming a .mac mail account.
If you have a pop account uncheck the box and it should show port 110.
.Mac uses 993.
Most pop accounts use 110.
So change your setting accordingly