Comcast Port 587 Not Working

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When doing port 587, it is wise to use your full e-mail address as your account name in password authentication, and your checking mail password for the same server as your password. Though the send mail server may differ from the receiving mail server. It might be:

smtp.comcast.net
mail.comcast.net
outgoing.comcast.net

Or you might need to try port 2626.
Or you might need to speak to a tier 2 support representative at Comcast,
and ask for your local neighborhood node name for all your internet access from your address. This sometimes ends up being the outgoing mail server on some Comcast accounts.

I recieved a similar email from Comcast saying "Comcast has determined that your computer(s) have been used to send unsolicited email ("spam"), which is generally an indicator of a virus."

I have no idea why I recieved this (waiting for a representative from Comcast Customer Security Assurance to call me back), but I'm sure it's related to the port change from 25 to 587.

Now I've been using port 465 for secure SMTP connections for... years probably. However, the configuration for server authentication seems to have changed.

The solution was to change the username under authentication from "userxyz" to "userxyz@comcast.net". (I use my primary Comcast username, in case that makes a difference.)

The best part was when I called Comcast and they told me I had to call Apple for help configuring the Mail.app client. Yeah, it's their problem.

Thanks, Carlos3543 . Using the full username made it work for me.