From https://help.yahoo.com/kb/SLN36803.html?guccounter=1 "I access my Comcast.net email through a third-party email client (like Outlook or iOS Mail). Will I still be able to access my email this way after my account is moved? Yes, but you'll need to complete your Comcast.net email move to Yahoo Mail first. Once you've accepted the Yahoo terms and have successfully signed in to your Comcast.net email at login.yahoo.com at least once, you'll then need to re-add your email account in the third-party email client using Yahoo Mail information." incoming IMAP server: imap.mail.yahoo.com, 993, SSL/TLS, OAuth2 authentication, email address outgoing SMTP server: smtp.mail.yahoo.com, 465, SSL/TLS, OAuth2 authentication, email address I think you can just change the current settings if the account is already IMAP, not re-add it. Enter the account password in the OAuth window when asked for access; an app password is not necessary. https://www.xfinity.com/support/articles/yahoo-email-migration-overview