Easy Peasy! Edit your account fromTools/Mail Settings and enter your key ID in the Security tab. Then either check Always sign outgoing mail when using this account or sign on a case-by-case basis by using the Security menu when composing a new message.
From a GPG Mini Howto:
These icons are the ones to the right of the default toolbar, showing a pen signing and a lock respectively. Keep in mind that you don't actually need to encrypt everything. Merely signing will often suffice unless you are paranoid or there's actually something you need to hide.
Download EnigMail, a plugin for Mozilla/Netscape here, install it, tell it which key ID to use, and it works.
It doesn't save your passphrase, and by default remembers it only for 5 minutes. You may wish to tweak this. By default it will sign outgoing mail, but you can change the default action, and when you email you can choose an option under the new EnigMail menu bar for default, signed, encrypted, signed + encrypted sends.
When Enigmail finds a key it doesn't know about, it downloads it for you then tells you that it's an unverified key.
set pgp_autosign yes
set pgp_replysign yes set pgp_replysignencrypted yes
The command to check the envelope on other people's messages is check-traditional-pgp, which is bound to [Esc? [Shift-p? in the index view by default.
If you see
unable to create PGP subprocess! --? -----END PGP SIGNATURE-----
then Mutt could not find gpg(1).
Get the GPG Plugin for Outlook Express (choose the "WinPT Outlook Express Plugin" link). Don't forget to configure the .reg file and tell it where your keys and GPG executable are kept.
Part of CategorySecurity
2 pages link to GPGMailClients:
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