Howto create Thunderbird Portable App with enigmail and MacGPG1 on an USB drive to encrypt your email
To secure your GPG-keys, you should put the whole newly created Portable Thunderbird Application (with enigmail and GPG inside) in a Truecrypt-Container and afterwards on an usb drive.
Create on the USB drive a file .gnupg/gpg.conf by opening the application Terminal and using the editor vi:
mkdir /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg vi /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg/gpg.conf verbose # debug-all # uncomment to debug # logger-file /Volumes/USB drive/gnupg.log # uncomment to debug no-default-keyring keyring /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg/pubring.gpg primary-keyring /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg/pubring.gpg secret-keyring /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg/secring.gpg trustdb-name /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg/trustdb.gpg # lock-never # uncomment if you have problems writing on a FAT32 partition, read http://www.gnupg.org/documentation/manpage.en.html
Install on your Mac MacGPG1 https://www.gpgtools.org/macgpg1/index.html
and copy /usr/local/MacGPG1 to your USB drive:
cp -r /usr/local/MacGPG1 /Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/
Afterwards you can uninstall macgpg1 from your mac using the deployed uninstall routine.
Install the enigmail add-on for your Thunderbird from http://www.enigmail.net and verify that OpenGPG uses the GnuPG from your USB drive. This can be done via the OpenGPG-Gui in Thunderbird with Show Expert Settings enabled or checking the corresponding profile/prefs.js entries:
user_pref("extensions.enigmail.agentPath", "/Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/MacGPG1/bin/gpg");
Also ensure that the portable keyring is used by giving additional parameters to GnuPG:
user_pref("extensions.enigmail.agentAdditionalParam", "--homedir \"/Volumes/USB drive/Portable Thunderbird/Portable Thunderbird.app/Contents/Resources/profile/.gnupg\"");
The OpenGPG Option use gpg-agent for passphrase should be unchecked to work locally on your usb drive.
Pictures for these two tasks you can find in the section Mac-only tasks before PGP key management on http://www.securelaptop.org/guidelines/create-a-pgp-key-pair
The "Portable Thunderbird.app" package content now looks as follows:
Tips to tune your Thunderbird performance are found at http://portableapps.com/support/thunderbird_portable#performance