Thunderbird 3 is excellent mail client with many useful functions, but automatic configuration of gmail accounts does not send the emails, however you can receive it. The problem is in smtp settings (outgoing mail), so here is tutorial how to set up gmail account correctly:

After automatic settings by Thunderbird 3.0, choose manual settings:

In the account Server Settings choose as below:

Server Name: imap.gmail.com
Port: 993
User Name: name@gmail.com or name@yourdomain.com (for google apps users)
Connection security: SSL/TLS
Use secure authentication: unchecked

In the Outgoing Server (SMTP) change the settings as below:

Server Name: smtp.gmail.com
Port: 465 Default: 465

Use name and password : checked
username: name@gmail.com or name@yourdomain.com (for google apps users)
Use secure authentication: unchecked
Connection security: SSL/TLS

After account creation you will be asked to enter your password and that’s it, your account is ready to use

Tags | Howto, Mozilla, Tutorials