Email Authentication Failed Error Message

I have tried to set up email access to one of my addresses in both Thunderbird and Mailbird using POP settings.

When the programs try to connect the return message is "mail.comcast.net responded: [AUTH] Authentication failed."

Previously the Mailbird account would receive but not send. I removed the account at Mailbird's suggestion and now it will not receive or send.

The Mailbird program has a connection TEST button and the connection fails, authentication again.

This failure began when Xfinity required me to change passwords a short while ago. Since then the connections have been NG,

I have double checked the input and it is ok. The same password will sign into Xfinity so I know that the password is good