1. Open System Settings and navigate to General -> Login Items.
2. Scroll down to find the applications listed under "Allow in the Background" and look for an entry named "Mailbutler GmbH".
3. If the switch was turned off, please turn it on and the issue should be resolved.
4. If the switch was already turned on, please turn it off and on again, then restart your Mac to see if the issue was resolved. If the issue unexpectedly persists, please contact our support.