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+# Mozilla Thunderbird
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Profiles](#profiles)
+   1. [Profile manager](#profile-manager)
+   1. [Backing up profiles](#backing-up-profiles)
+   1. [Restoring profiles from backups](#restoring-profiles-from-backups)
+1. [Sources](#sources)
+
+## TL;DR
+
+## Profiles
+
+Sets of files where Thunderbird saves personal information such as messages, passwords and user preferences.<br/>
+One can have multiple profiles, each containing a separate set of user information.
+
+The Profile Manager allows to create, remove, rename, and switch profiles. 
+
+### Profile manager
+
+When Thunderbird is open:
+
+1. Open the hamburger menu on the top right, or look at the menu bar.
+1. Choose _Help_ > _Troubleshooting Information_.
+1. On the page that opens, click the _about:profiles_ link.
+
+When Thunderbird is closed:
+
+```sh
+/Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin --ProfileManager
+${HOME}/Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin -P
+```
+
+### Backing up profiles
+
+1. Close Thunderbird if it is open.
+1. Copy the profile folder to another location:
+   ```sh
+   cp -a "${HOME}/Library/Thunderbird/Profiles/we12yhij.default" "/Backup/Thunderbird/we12yhij.default"
+   ```
+
+### Restoring profiles from backups
+
+1. Close Thunderbird if it is open.
+1. If the existing profile folder and the profile backup folder have the same name, replace the existing profile folder with the profile backup folder:
+   ```sh
+   rm -fr "${HOME}/Library/Thunderbird/Profiles/we12yhij.default"
+   cp -a "/Backup/Thunderbird/we12yhij.default" "${HOME}/Library/Thunderbird/Profiles/we12yhij.default"
+   ```
+   > Important: The profile folder names must match exactly for this to work, including the random string of 8 characters.
+1. If the profile folder names do not match, or to move or restore a profile to a different location:
+   1. Use the Profile Manager to create a new profile in the desired location, then exit the Profile Manager.
+   1. Open the profile's backup folder.
+   1. Copy **the entire contents** of the profile's backup folder.<br/>
+      This includes the `mimeTypes.rdf`, `prefs.js` and the other files.
+   1. Locate and open the new profile folder.
+   1. Paste the copied contents into the new profile's folder.<br/>
+      Overwrite existing files of the same name.
+   1. Open up the `profiles.ini` file in the application data folder in a text editor.
+      ```sh
+      vim "${HOME}/Library/Thunderbird/profiles.ini"
+      ```
+   1. Check the `Path=` line for the profile is correct.
+1. Start Thunderbird.
+
+## Sources
+
+- [profile manager create and remove thunderbird profiles]
+- [Profiles - Where Thunderbird stores your messages and other user data]
+
+<!--
+  References
+  -->
+
+<!-- Upstream -->
+[profile manager create and remove thunderbird profiles]: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#
+[profiles - where thunderbird stores your messages and other user data]: https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#