Outgoing server (SMPT) ERROR

We know exactly what you tell us. So providing the actual error, verbatim, is one of the best ways to get an answer that is not pure guess work.

I can't send email from comcast.net account. Outgoing server (SMPT) ERROR. Comcast said problem with mozilla. What should password be for comcast smtp://smtp.comcast.net (smtp://smtp.comcast.net)?

Send message error: Sending error occurred while sending mail. Outgoing server (SMTP) error. The server responded: resomta-a2p-647652.sys.comcast.net resomta-a2p-647652.sys.comcast.net. Excessive failed authentication, ESMTP server temporarily not available.

I use 2 step verification on my comcast account