This guide shows staff how to properly connect Thunderbird to Mailcow for:

• Email (IMAP + SMTP)
• Calendar (CalDAV via SOGo)

Important: If your account has 2FA enabled, you must use an App Password. Thunderbird will not work with your normal login password.

1. Create an App Password in Mailcow

1. Log in to your Mailcow webmail account.
2. Open the Mailbox menu.
3. Select App Passwords.
4. Click Create app password.
5. Name it something like: Thunderbird.

6. Choose allowed protocols:

   • IMAP
   • SMTP
   • DAV (for calendar)
7. Copy the generated password.

2. Configure Email in Thunderbird

1. Open Thunderbird.
2. Go to Account Settings → Add Mail Account.

3. Enter:

   • Your full email address
   • Any name you prefer
   • App Password from Mailcow (NOT your main password)
4. Thunderbird should auto-detect settings.

Required server settings

• Incoming (IMAP):

  • Host: Your Mailcow server domain
  • Port: 993
  • SSL: SSL/TLS
  • Authentication: Normal Password

• Outgoing (SMTP):

  • Host: Your Mailcow server domain
  • Port: 465 (or 587 if needed)
  • SSL: SSL/TLS
  • Authentication: Normal Password

3. Enable CalDAV Calendar in Thunderbird

Mailcow uses SOGo for calendar sync.

1. In Thunderbird, go to Calendar.
2. Click + New Calendar.
3. Choose On the Network.
4. Select CalDAV.
5. Enter your calendar URL (example format below):

https://your-mailcow-server/SOGo/dav/your-email/Calendar/personal/

6. When prompted:

   • Username: Your full email address
   • Password: Your App Password

7. Complete setup.

4. Common Issues to Avoid

• Using your main password instead of an App Password → causes "wrong credentials".
• Forgetting that the calendar URL must end with a trailing slash /.
• Choosing the wrong authentication type (must be Normal Password).

• Having saved old passwords in Thunderbird. You may clear them here:

  • Settings → Privacy & Security → Saved Passwords → Remove old entries.

5. Verification Checklist

• Email works for sending and receiving.
• Calendar events appear in Thunderbird.
• Your App Password is active in the Mailcow App Passwords list.

> Screenshot suggestion: Calendar list in Thunderbird showing the subscribed CalDAV calendar.

If these steps are followed, Thunderbird will reliably sync both email and calendar with Mailcow.