Are messages arriving in the webmail Inbox but not downloading to TB? If they are, the first thing to check is for a corrupted message:

https://support.mozilla.org/en-US/questions/1301414

Check for correct server settings:

https://www.xfinity.com/support/articles/email-client-programs-with-xfinity-email

Hi Folks, after I sent the prior message (listed below) to you my download worked properly the following day. Then it stopped working again. I have tried several different methods to get things started again but nothing has worked so far. Thoughts?

new thunderbird version 115.3.3 (64 bit) will not download emails from xfinity

Hi Folks, after I sent the prior message (listed below) to you my download worked properly the following day. Then it stopped working again. This is now the 2nd time this has happened. What has to be done to permanently correct this problem?

new thunderbird version 115.3.3 (64 bit) will not download emails from xfinity

If the issue is sporadic, I think the settings are correct, but maybe you periodically receive a particular message that blocks the download of the other messages. Access through webmail, empty Trash and Spam/Bulk, and see if there is a recurring message (most likely commercial) that appears before downloads to TB fail.

Have tried numerous things to correct "not downloading" problem but nothing has changed with respect to getting messages since the Thunderbird update. Had no problems before that.

If it started after a TB update, maybe an external app like antivirus became incompatible with the update. Check if the AV is scanning the profile folder, and if it is, add the folder as an exclusion or exception.

Hi there, worked for a few days and then stopped downloading again. I tried the following as you recommended:

"If it started after a TB update, maybe an external app like antivirus became incompatible with the update. Check if the AV is scanning the profile folder, and if it is, add the folder as an exclusion or exception."

I was unable to find the profile folder after a lengthy search so I could not do what you recommended. Emails not downloading. Anything else I can do?

What is the antivirus? If it's something like AVG/Avast, turn off Mail or Email Shield.

The profile folder location is found from Help/Troubleshooting Info, Profile Folder, Open Folder.

I had the same problem. After changing password for xfinity, I could not get any email updates, even after changing it in TB. my solution was to delete the account and reinstall it using the autosetup. After typing in the new password and testing, the connection tested good and all my emails returned. I just hope I don't have to do this everytime I change my password.