Sending problems with secure.mailbox

It may happen that emails from mailbox Office cannot be sent if you have enabled Encrypted sending in the settings. Please check this setting first.

If it is enabled, you may receive an error message like the following after trying to send an email from your secure address:

(In this example: max.mustermann@mailbox.org tries to send an email via their secure address to schmidt@example.com)

The mail system
schmidt@example.com>: mail transport unavailable

--C02BF40022.1392494027/mxtls1.mailbox.org
Content-Description: Delivery report
Content-Type: message/delivery-status
X-Postfix-Sender: rfc822; max.mustermann@secure.mailbox.org
Final-Recipient: rfc822; schmidt@example.com
Original-Recipient: rfc822; schmidt@example.com
Action: failed
Status: 4.3.0
Diagnostic-Code: X-Postfix; mail transport unavailable

Cause

When you use your secure address, we transport the email from our mail server exclusively via encrypted connections to the recipient's mail server.

Unfortunately, not all mail servers support encrypted connections. In this case, the following happens:

• Our server will attempt email delivery for a total of 3 hours.
• If no encrypted connection to the recipient’s mail server can be established within this time, the delivery will fail – resulting in exactly the error message shown above.
• The message will not be sent unencrypted.

Background

This is not a bug (an undesired result caused by a software error), but rather intended behaviour.

This ensures that your emails are never sent insecurely via unencrypted connections.

Recommendation

Inform the recipient about this issue so that they can configure (or have configured) their mail server according to current security standards.