Disappearing Emails

As a precaution, I would change your password to something stronger than whatever it is right now, and also change your secret question and answer. Suddenly vanishing emails is a common sign of a malware infection or a compromised account. Run a complete scan of your machine with your A/V software to see if it finds anything wrong. There are no editable deletion schedules in the new format.

Also, do you have another device like a smartphone or tablet with the account enabled on it? If so it may be downloading and then deleting the messages from the server. Check all the settings in it to see if that's what's going on.  If it's not that, call Comcast security and see if they can recover the missing emails-------------------

Comcast Customer Security Assurance-------------------

Normal business hours (6:00 am to 2:00 am EST, 7 days a week)

1 - 888-565-4329

Thank you for that advice, I already changed my password recently so I don't think it was a hacking incident.  However, after spending close to an hour on the phone with an Xfinity tech, my emails were recovered by opening recovered mail from trash from the additional actions icon by trash. I had checked my trash, but not the icon with the 3 lines.  It also allowed me to move them back to my inbox. The tech admitted it was a systemic glitch. Hopefully it's fixed for good!

Try turning off Access to third party email servers. Instructions here:

https://www.xfinity.com/support/articles/third-party-email-access