I can receive and send mail on my Comcast.com mail.  I can receive mail on my Windows Live mail but as of today only can't send mail.  I get this error:

An unknown error has occurred.

Windows Live Mail Error ID: 0x800C006C
Protocol: SMTP
Port: 0
Secure(SSL): No

I am using the Pop 3 for incoming:  mail.comcast.net and for outgoing SMTP: smtp.Comcast.net  For the settings on incoming it is 995 and outgoing: 587.  It has been working up until today.  I haven't done anything different and Xfinity agent said everything looks fine.  Why can't I send mail all of a sudden?  Is there another outgoing number I can use?  25 doesn't work either.

Moved from: Windows / Windows 7 / Email & communications