Connect mailbox.org

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You connect mailbox.org over CalDAV with your mailbox.org address and an application password. You create it in two minutes right in your mailbox.org settings — after that everything runs automatically, and sync picks up changes every 5 minutes.

The most common pitfall

For external programs like Kalender Sync, you create a dedicated application password at mailbox.org. If you have two-factor authentication enabled it’s mandatory — your regular password no longer works here. Without 2FA the application password is optional, but recommended.

1. Create an application password

1. Sign in to mailbox.org and open “Settings” → “Security” → “Application Passwords”.
2. Choose the application “Calendar and address book client (CalDAV/CardDAV)” and give it a label (e.g. “Kalender Sync”).
3. Click “Add new password”.
4. Copy the password shown — for security reasons it’s only displayed once.

2. Connect in Kalender Sync

1. In the dashboard: “Connect calendar” → “mailbox.org” → “Continue” to the form.
2. Enter your mailbox.org email address (e.g. name@mailbox.org).
3. Paste the application password and click “Test & Connect” — Kalender Sync verifies the connection immediately.

You don’t need to enter the server address — Kalender Sync knows it and finds your calendars automatically.

If “sign-in failed” appears

• Did you really use the application password, not your regular mailbox.org password?
• Best to paste the password fresh instead of typing it.
• Password deleted in your mailbox.org settings in the meantime? Simply create a new one (step 1).

Birthday calendar

mailbox.org automatically creates a “Birthdays” calendar. At mailbox.org it is read-only — use it at most as a source for a one-way sharing, not as the target of a two-way sync.

Ending access

In Kalender Sync: remove the calendars. You can also delete the application password any time in your mailbox.org settings under “Security” → “Application Passwords” — access ends immediately.