The instructions and screenshots in this setup guide are for the latest version of Thunderbird, which you can download for free for Windows, macOS, or Linux.
You can easily add your Fastmail account to Thunderbird using the setup guide in the Settings → Import & Setup screen. The general setup instructions are below.
Thunderbird needs its own app password to access your information. If you use your normal password in Thunderbird, syncing won't work and you will see a password error.
Set up your email
Open Thunderbird. The Set Up an Existing Email Account dialog box will appear. If it doesn't, select Local Folders in the sidebar on the left, then under the Set up an account heading in the page that appears, click the Email link.
Fill in your name, email address, and app password:
- Your name: Whatever name you want others to see on the email you send.
- Email address: Your full Fastmail username, including the domain.
- Password: Your Thunderbird app password. (What is an app password?)
Click Continue. Thunderbird will find the server settings.
Click Done. Thunderbird will fetch the list of your folders and start synchronizing your mail. If you wish to sync calendars, this can be done now (see below for further instructions).
Adding your other email addresses
To use a different email address to your Fastmail username:
- Open Thunderbird. Click your account name in the sidebar (just above the Inbox).
- Click View settings for this account.
- Click Manage Identities…, then click Add…
- Fill in Your Name and Email Address with the name and email you want your messages to come from.
- Click OK to save the new identity. If you want it to be the default, click Set Default then close the identities panel. Click OK to close the account settings dialog.
You will now be able to choose the address you added to send messages from when you compose new messages in Thunderbird.
Set up your calendar and contacts
You can sync Fastmail calendars and contacts during initial setup of your account in Thunderbird.
- When you have set up your mail account and reach the Account successfully created screen, Thunderbird will then search for any other services you can link to for your account. If Thunderbird detects that your account has any address books or calendars that can be linked, you should see these options show up under Connect your linked services.
- If you wish to set up contacts, click on the Address Book dropdown. You can choose which address books to link by clicking the Connect button next to the corresponding address books.
If you wish to set up calendars, click on the Calendars dropdown. You can choose which calendars to link by clicking the Connect button next to the corresponding calendar. A popup window will appear showing settings you can choose for linking this calendar. Choose your preferred settings and click Connect to complete the link.
- After you've linked the preferred services, click Finish.
Repeat these steps to add any other calendars or address books in your Fastmail account.