My home Comcast emails just quit two days ago.  I was using POP.  The new Comcast settings are for IMAP.  So I reloaded the Windows Live Mail 2012/ Essentials program and rebooted.  Then removed the accounts and put in new accounts with IMAP.  Now I can receive but no sent emails.  I followed Comcast Sheet of instructions dated May 15, 2015.  IMAP account Incoming IMAP on 993   with outgoing smpt on 587 with SSL checked on both.  Then I have changed port numbers around etc to no avail.  Every time I send a email it, small box,  says to retry there is a problem   and the last error message was different:

Your IMAP command could not be sent to the server, due to non-network errors. This could, for example, indicate a lack of memory on your system.
Configuration:
   Account: Comcast (xxxxxxxxl)
   Server: imap.comcast.net
   User name: xxxxxxxx
   Protocol: IMAP
   Port: 993
   Secure(SSL): 1
   Code: 800ccc0e

instructions from Comcast:

http://customer.xfinity.com/help-and-support/internet/email-client-programs-with-xfinity-email

http://customer.xfinity.com/help-and-support/internet/connect-on-windows