Turn Thunderbird into the Ultimate Gmail IMAP Client

Buscando cómo hacer que al borrar los mensajes de la bandeja de entrada de Gmail, Thunderbird los mueva a la carpeta Trash (Papelera) de Gmail he encontrado este artículo muy interesante:
Turn Thunderbird into the Ultimate Gmail IMAP Client
Donde explican:

Set Thunderbird to use Gmail's Trash folder (UPDATE)

Reader Vanl explains how to set T-bird's trash folder correctly, which involves some Thunderbird configuration editing. Here's how:

1. From the Tools menu, choose Options.
2. Go to the "Advanced" Option menu and the "General" tab. Hit the "Config Editor" button next to the "Advanced Configuration" label.
3. Now you need to look around in there a bit to find which server you need to modify. Using the filter entry box at the top, type in mail.server.server and you will see a list of keys and values. One of those keys will be mail.server.serverX.name, where X is a number and the value is the name of your Gmail IMAP account. Remember X.
4. Right-click somewhere in the box and select New->String.
5. A dialog box will pop up asking for the name of your new key. Put in mail.server.serverX.trash_folder_name, where X is the number you remember from above. (For example, mine is mail.server.server2.trash_folder_name.)
6. A new box will come up asking for the value of your new key. Put in [Gmail]/Trash.
7. Go to Gmail's web interface and delete the label [Imap]/Trash.
8. Restart Thunderbird.