How to switch from macOS Mail, Address Book and Calendar to Thunderbird


Thunderbird is one of the most popular email programs available on Linux. It is made by Mozilla who is also the people behind Firefox. It is made by a community of volunteers and a few paid developers funded by the Thunderbird community. Thunderbird comes installed by default in Ubuntu and many other distros. There are other alternatives, but Thunderbird is full-featured and extensible and a good place to start. (Once you are using open standards for storing your email, migrating to another email program if you should desire to do so should be trivial.) If you are planning to switch from Mac OS or Windows to Linux, it is often smart to migrate slowly by switching out some programs first and then changing operating system when you have become accustomed to the new programs you will be using. Thunderbird is one of the many free and open source programs that are available for Mac, Linux and Windows. The free and open source software community are generous even with users of non-free and non-open source operating systems even if it takes extra time, effort and money to port software over, so you might want to contribute back with some money, design, translation, bug reports or coding if you appreciate the software.

If you are going to use Thunderbird on Linux, but do not plan to use it on macOS, you still need to download it on macOS. This is because the easiest way to migrate from Address Book, Mail and possibly Calendar on macOS to Thunderbird on Linux is to first use Thunderbird on macOS to import everything and then copy your profile folder from macOS over to Linux. Have a look at this page to learn more about Thunderbird profiles. It is not possible to directly import your email account settings from macOS Mail, so you have to enter those manually. The easiest way to do this is simply to have both programs open at the same time and copy the information from Mail to Thunderbird.

Thunderbird has got extensions, which means that it is possible to make it even more useful. The most popular extension is Lightning, which adds a calendar tab to the program. This is a good option if you do not want to use a separate calendar program on Linux. Lightning can both import calendars from macOS Calendar and sync with CalDAV calendars online such as Google Calendar, Owncloud calendars etc. You can also install further extensions to make it sync with Microsoft’s Exchange calendars and mail (Outlook). As of 2018, Lightning is now built into Thunderbird and you no longer need to install it separately.

Importing email from macOS Mail to Thunderbird on macOS

  1. Open Thunderbird on your Mac.
  2. Choose “Import” from the “Tools” menu.
  3. Select “Mail” then click the “Next” button.
  4. Select “Apple Mail” then click “Next” again.
  5. Click “Finish”.

After you have imported your email, you will see a folder called “Apple Mail Import” which has all your local folders from macOS Mail inside. You can move all the folders inside this folder outside it if you want.

Importing your contacts from macOS Address Book

When you use Thunderbird on macOS, it can use contacts from the macOS Address Book directly. In principle, it should be possible to import contacts directly from the Address Book into Thunderbird by dragging and dropping them from one window to the other, but at least when I last tried some years ago, this did not work. I also had trouble with importing a .vcf file with all contacts from Address Book into Thunderbird on Mac OS X. It only imported some contacts and left the rest blank or half blank and it seemed to be especially problematic for names with Scandinavian characters. However, I found another way that did work. The way to do it is to convert the .vcf file you export from macOS Address Book into a .csv file in the ldif format that Thunderbird supports. You could use this method both for importing to Thunderbird on macOS and Linux.

This is how you do it:

  1. Select all your contacts in Address Book (hit cmd-a) and drag your contacts to the desktop. This creates a .vcf file.
  2. Rename the file to the name you want for this group of contacts in Thunderbird.
  3. Open in your browser.
  4. Press “Select file…” and choose your .vcf file.
  5. Click “Convert” and wait for it to finish.
  6. Open Thunderbird.
  7. Choose “Address Book” from the “Tools” menu.
  8. Choose “Import…” from the “Tools” menu in the Address Book Window.
  9. Choose your .csv file

Importing your calendar from macOS Calendar

If you have the Lightning extension installed, you can import .ics (iCal) files and Outlook calendars (.csv files) to use in Thunderbird.

  1. Open Calendar.
  2. Select the calendar you wish to export from the sidebar.
  3. Choose “Export” from the “File” menu and save your file.
  4. Open Thunderbird.
  5. Choose “Import…” from the “Events and tasks”.
  6. Repeat the process for each calendar you wish to export/import from Calendar to Thunderbird.

Copying the profile folder from macOS to Linux

If you want to use the contacts, emails, email settings and calendar you have set up on Thunderbird on macOS on Linux, you have to copy the profile folder from your Mac to Linux. The easiest way is to use a USB stick to copy the data over. Depending on how many mails you have saved and especially how many attachments those emails contain, your profile might take anything from almost no space to a number of gigabytes, so use a USB stick with enough storage space.

  1. Insert your USB stick on your Mac.
  2. Open a new Finder window and navigate to your home folder.
  3. Open the Library folder.
  4. Open the Thunderbird folder.
  5. Copy the folder that has a name that ends in “.default” over to your USB stick. Wait for the copying to finish.
  6. Click the eject button in Finder and take out the USB stick.
  7. Start your Linux machine (or if you are running Linux on your Mac, restart your Mac and choose Linux instead of macOS).
  8. Insert your USB stick.
  9. Open your file manager and navigate to your home folder.
  10. Choose “Show hidden files” or press ctrl-h.
  11. Make a new folder called “.thunderbird” if it does not already exist. (If there already exists a “.thunderbird” folder, open it and delete any folders inside it that has a name that ends with “.default.”)
  12. Copy the folder with the name that ends in “.default” into the “.thunderbird” folder.
  13. When the copying finishes, open Thunderbird to check that all your stuff is there.

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