It is likely that the password is correct but you are using the wrong authentication method. For gmail access here are the server settings I use in TBird:
Server Name: imap.googlemail.com
Port: 993
User Name: xxx@gmail.com
Connection security: SSL/TLS
Authentication method: Normal password
For your outgoing mail, configure the smtp server as follows:
Server Name: smtp.googlemail.com
Port: 465
User Name: xxx@gmail.com
Authentication method: Normal password
Connection security: SSL/TLS
Hope this helps,
Hayo