I want to include a text file containing my GPG public key in all the mails that I send using Mozilla Thunderbird.
Is there any way to configure Thunderbird to automatically include this file whenever I compose a new message?
I'm a Windows user myself so the instructions below apply to the Win version, but the Ubuntu version should be similar.
You can include a link to your public key file in your signature. That way a bulky .asc file isn't included with every email.
If it is, however, your intention, to include your public key with every message, here's what you do:
Right-click the account for which you want to add a signature and choose SETTINGS. You can also go to the ACCOUNT SETTINGS screen via TOOLS menu.
Click ATTACH SIGNATURE FROM FILE and point TB to the .asc (or similar) file containing your public key. This will result in your public key text block appearing as your signature. Your public key will be embedded within the message and not as a separate attachment, however.
Grab Enigmail and install it. It'll do all you ever want with GPG and Thunderbird, guaranteed :-).