email & pgp: added fairmail and linked pgp and email entries

wiki/android/fairemail.md

@@ -1,7 +1,7 @@
 # FairEmail
 
-[FairEmail](https://email.faircode.eu/) is a free and open-source email client for
-[Android](/wiki/android.md).
+[FairEmail](https://email.faircode.eu/) is a free and open-source
+[email client](/wiki/email.md#client) for [Android](/wiki/android.md).
 
 ## Setup
 

wiki/email.md

@@ -1,10 +1,10 @@
-# E-mail
+# Email
 
-E-mail is a method of exchanging electronic messages.
+Email is a method of exchanging electronic messages.
 
 ## Setup
 
-E-mail usually consists of a [server](#server) and a [client](#client).
+Email usually consists of a [server](#server) and a [client](#client).
 
 ## Server
 

wiki/office_suite.md

@@ -1,7 +1,7 @@
 # Office Suite
 
 An office Suite are bundled programs that usually include productivity tools like word processing,
-spreadsheet editing, presentations aswell as e-mail and calendar software.
+spreadsheet editing, presentations aswell as [email](/wiki/email.md) and calendar software.
 
 ## Programs
 
@@ -18,3 +18,8 @@ The following is a list of programs that are popular.
   and [Linux](/wiki/linux.md).
   Most of the time this suite is not used anymore in favor for LibreOffice due to lackluster
   development.
+
+Additionally to the full fledged office suites programs such as
+[email clients](/wiki/email.md#client) exist.
+Those are not part of the office suite category by definition but are at least adjacent and have to
+be mentioned here aswell.

wiki/openpgp.md

@@ -9,3 +9,12 @@ There are different implementations of OpenPGP.
 Many [Linux](/wiki/linux.md) [package managers](/wiki/linux/package_manager.md) 
 package the implementation called [Gnu Privacy Guard](/wiki/linux/gpg.md) in the `gnupg` or
 sometimes also `gpg` or `gpg2` package.
+
+## Usage
+
+This section addresses the usage of OpenPGP.
+
+### Encrypting, Decrypting, Signing and Verifying Emails
+
+OpenPGP is often used to encrypt, decrypt or sign [emails](/wiki/email.md).
+Most modern [email clients](/wiki/email.md#client) feature a way to do that.

wiki/thunderbird.md

@@ -1,7 +1,7 @@
 # Thunderbird
 
 [Thunderbird](https://www.thunderbird.net/en-US/) is a free and open-source program to manage
-numerous e-mail addresses, calendars, todos and contacts.
+numerous [email](/wiki/email.md) addresses, calendars, todos and contacts.
 
 ## Usage