NOTE: In Debian Thunderbird is called Icedove and the package is icedove.
## Mac OS X
You need PGP-tools, Thunderbird and Enigmail
## Windows
You need GPG4Win, Thunderbird and Enigmail.
# Running the Enigmail wizard.
If Enigmail wizard doesn't appear by itself, open it manually from OpenPGP (menu) --> Enigmail wizard.
NOTE: Allow wizard to do changes, which it wants.
## Enable viewing messages in original HTML.
instructions here
## If the wizard fails
Write with computer
## Sending UTF-8
Write to Icedove / Thunderbird guide.
# Testing that everything works
Write about Adele
# Sending PGP/MIME instead of PGP/INLINE
I personally don't recommend this, because of my reasons. PGP/MIME puts the signature to signature.asc attachment and PGP/INLINE into "mess" in the bottom of email.