1. Check your spam folder for messages that may have been mislabeled.
2. Rewrite, update, and review email filter settings to ensure that auto-replies are being routed correctly.
3. Check permissions on specific folders to verify that users have the correct access rights.
4. Ensure that your email server is configured correctly and that the correct mail transfer agent is selected.
5. Troubleshoot any connectivity issues with any external servers.
6. Verify that your auto-reply address is still active and associated with the correct account.
7. Check that there are not multiple auto-reply messages in conflicting settings.
8. Review your server logs to look for any errors in email routing.