Comcast uses te Xfinity server and there are very specific settings you must use.

Password means the use the same password you use to access the webmail account. I understand you have accessed webmail and modified/updated the password.

First check that new password still gets you access to the webmail account. If yes. Good.

Now check you have the correct outgoing server settings for the account. Outgoing server SMTP settings:

• Server name: smtp.comcast.net
• Port: 587
• Connection Security: STARTTLS
• Authentication Method: Normal Password
• Username: full comcast email address

As you modified the password then this is what you need to check:

• In Settings > Privacy & Security
• Password section
• Click on 'Saved Passwords'
• Click on 'Show Passwords'

There should be two lines for the account. If you use Pop you will see: mailbox://account.... If you use imap then you will see: imap://account... You will also see the outgoing: smtp://account....

• Right click on each relevant line and select 'Edit Password'
• Completely clear everything and then carefully type the correct password.
• Click on 'Close' when done

Exit Thunderbird, wait a few moments and restart.

Yes this solves the issue. Note that the settings you supplied worked and are different than the Xfinity instruction settings,! Thank you