added fairemail and improved thunderbird pgp

wiki/android/fairemail.md

@@ -0,0 +1,33 @@
+# FairEmail
+
+[FairEmail](https://email.faircode.eu/) is a free and open-source email client for
+[Android](/wiki/android.md).
+
+## Setup
+
+On [Android](/wiki/android.md) FairEmail is available on [F-Droid](/wiki/android/f-droid.md) in a
+package called [FairEmail](https://f-droid.org/en/packages/eu.faircode.email/).
+Additionally it is available on the[Google Play store](/wiki/android.md#app-store) in a package
+called [FairEmail](https://play.google.com/store/apps/details?id=eu.faircode.email&hl=de).
+
+## Usage
+
+This section addresses the usage of FairEmail.
+
+### Use PGP Key for Encryption, Decryption and Signing
+
+FairEmail can use [OpenPGP](/wiki/openpgp.md) to sign, encrypt or decrypt mails.
+To achieve this download [OpenKeychain](https://www.openkeychain.org/).
+To connect FairEmail with OpenKeychain navigate to the settings and select `Encryption`.
+There the provider of OpenPGP (`OpenPGP provider`) can be set to OpenKeychain
+(`org.sufficientlysecure.keychain`).
+Using OpenKeychain PGP keys can then be imported and stored.
+
+After this is done outgoing mails can be encrypted by signed or encrypted by selecting the
+`Encrypt` selection on the top bar when writing emails.
+
+Decryption can be done by clicking on the padlock when inside an email that is encrypted.
+
+Additionally in the settings under `Encryption` the signing (`Sign by default`), encryption
+(`Sign and encrypt by default`), decryption (`Auomatically decrypt messages`) and validation
+(`Automatically verify signed messages`) can be set to occurr automatically.

wiki/mail.md

@@ -22,6 +22,8 @@ And even if you have it can be useful to keep your mails synced locally on your
 
 - [Neomutt](linux/neomutt.md) is a [terminal-based](/wiki/linux/system_console.md)
   mail client for linux, that has a simple interface.
-- [Thunderbird](/wiki/thunderbird.md) is a free and open source mail client which is cross
-  platform.
+- [Thunderbird](/wiki/thunderbird.md) is a free and open-source mail client which is
+  cross-platform.
   It also features, contact, todo and calendar management.
+- [FairEmail](/wiki/android/fairemail.md) is a free and open-source mail client for
+  [Android](/wiki/android.md).

wiki/thunderbird.md

@@ -16,6 +16,12 @@ There keys can be added by selecting `Add Keys...` and afterwards the private ke
 for encryption, decryption and signing.
 This however is only possible if the key is issued to the same e-mail it should be added to.
 
+In the `Account Settings` of emails with set up PGP key the default options can be set up.
+Under `Deault settings for sending messages` it can be set to encrypt or not encrypt mails by
+default.
+Emails can also be signed by default if not encrypted (for this select
+`Sign unencrypted messages`).
+
 ### Enable Spell Checking of a Specific Language
 
 Spell checking can be changed in the `Settings` from the `Edit` tab.