smtp.comcast.net *or* smtp.comcast.net:587
*or* smtp.businessclass.comcast.net:587 (for business accounts)
ESMTP | Login
Note that Comcast has a delivery limit of 3 connections and 1'000 deliveries per day.
As a precautionary measure to stop spam, many ISPs are no longer allowing outbound traffic on port 25. As a result, your ISP may have blocked port 25 on your account. Port 25 is the standard TCP port used to send e-mail via the SMTP protocol. Hopefully most SMTP servers offer their services through several ports. So, if MaxBulk Mailer can't connect to your server through default port 25 try to use port 587 or 2525. Note that the Comcast Business Class account doesn't block port 25 however you will need to use the following as your SMTP host: 'smtp.businessclass.comcast.net:587' without quotes. You may also need to set security to TLSv1.2
WAIT! In order to add a comment below just use your Facebook, Google+, Twitter or Disqus login data.