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Mozilla Thunderbird

Recommended for mailcow

We recommend using this client in combination with our mailcow software for smooth operation and hassle-free emailing.

What is Thunderbird?

Thunderbird is a free and open-source email client developed by the Mozilla Foundation. It supports multiple email accounts (IMAP, POP3), contacts, calendars, and add-ons to extend its functionality. Thunderbird is known for its high compatibility, user-friendly interface, and extensive customization options, making it particularly well-suited for use with mailcow.

Setup Instructions on Desktop

Note

Please ensure that you have configured the advanced DNS settings to enable smooth automatic detection of your mail settings.

  1. Open Thunderbird.
  2. If this is your first time opening Thunderbird, you will be prompted to create a new email address. Click Skip this and use my existing email address and continue with step 4.
  3. Click on the File menu and select New → Existing Mail Account....
  4. Enter your name (), your email address (), and your password. Make sure Remember password is checked and click Continue.
  5. Once the configuration is detected automatically, ensure IMAP is selected and click Done.
  6. To use your contacts from the server, click the arrow next to Address Books and then click Connect for each address book you want to use.
  7. To use your calendars from the server, click the arrow next to Calendars and then click Connect for each calendar you want to use.
  8. (Optional) If you want to synchronize all subfolders:
    • Open the Account Settings menu and select Server Settings.
    • In the Server Settings tab, click the Advanced button.
    • In the Advanced Account Settings window, uncheck Show only subscribed folders.
    • Click OK to save the changes.
  9. Click Finish to close the account setup window.

Setup on Android (Thunderbird Mobile / K-9 Mail)

As of version 115, Thunderbird for Android is based on the well-established app K-9 Mail. The setup is similar:

  1. Install K-9 Mail or Thunderbird for Android from the Google Play Store or F-Droid.
  2. Open the app.
  3. Tap Add Account or the "+" icon on the start screen.
  4. Enter your email address and password, then tap Manual Setup.
  5. Choose IMAP as the account type.
  6. Enter the following information:
    • IMAP Server: your MAILCOW_HOSTNAME
    • Security: STARTTLS or SSL/TLS
    • Port: 993 (SSL) or 143 (STARTTLS)
    • Username: your email address
  7. For the SMTP server:
    • SMTP Server: your MAILCOW_HOSTNAME
    • Security: STARTTLS or SSL/TLS
    • Port: 465 (SSL) or 587 (STARTTLS)
    • Username: your email address
  8. Tap Next, optionally set a display name for the account, and complete the setup.

K-9 Mail does not support native CardDAV or CalDAV synchronization. For contacts and calendars, we recommend using the additional apps DAVx⁵ or ICSx⁵.