Verify that the Incoming Server Host Name is filled with imap.comcast.net and make sure that 993 is selected in the Incoming Mail server port field.
Under Outgoing Mail Server, verify the outgoing mail server name smtp.comcast.net and check 587 is selected in the Server Port field.
If the fetch settings are configured incorrectly, go to Settings and tap the Passwords & Accounts tab.
Under Accounts, tap the Fetch New Data button to allow the Mail app to check for new email messages.
If all the troubleshooting steps had failed to work, remove and reconfigure your Comcast account on your iPhone.
Make sure to configure the correct server settings while setting up your Comcast account again in the Mail app.
If you have any difficulties, click Call to contact our technical support team and they will assist you in fixing your Comcast email stopped working on iPhone issue.