Turn on access
Xfinity blocks other email apps until you allow them. Switch that on once, in your Xfinity settings.
Help
Your comcast.net address works with Patriot Mail. Comcast is moving Xfinity Email over to Yahoo, a few customers at a time, so some accounts have moved and some have not. There is no way to tell from your address. This page covers both, starting with the one most people need.
Step 1 - Required
Open xfinity.com in a browser and sign in with your usual Xfinity details.
Go to your email, open Settings, then Security. Xfinity keeps the setting for other email apps there.
Switch on the setting that lets other email programs get your mail, then save.
Step by step
Go to Settings, then Accounts, then Add New Account.
Type your full comcast.net address. Patriot Mail fills in the Comcast server settings for you.
Use the same password you use on the Xfinity website, then continue.
If that did not work
Open connect.xfinity.com in a browser. If your account has moved, you are asked to accept Yahoo terms once.
In your Yahoo account security settings, generate an app password. It is a one-off password made for email apps.
Incoming imap.mail.yahoo.com on port 993 (SSL). Outgoing smtp.mail.yahoo.com on port 465 (SSL). Use the app password instead of your Xfinity one.
Still stuck
Related guides
If Comcast has moved your account to Yahoo, this guide covers app passwords in more detail.
Open Yahoo GuideServer settings and ports for Comcast and other common inboxes for manual setup.
Open IMAP GuideContact the support team if your account still will not connect.
Open Support