Displayed reason in the Control Panel: 554 5.7.1 <user@domain.tld>

If the error 554 5.7.1 is shown in the Control Panel, the affected mailboxes are usually not yet known on all servers or have not been set up correctly.

The onboarding is complete, the MX records point to our systems, and emails are already routed through our systems, yet incoming emails to newly created mailboxes are initially rejected.

The cause depends on which user verification is set in the Control Panel. User verification determines how Hornetsecurity checks whether a recipient mailbox exists.

Common cases in troubleshooting:

1. User verification set to Control Panel – Mailbox recently created

If user verification is set to Control Panel and the mailbox was created recently, the Control Panel still needs some time to roll out the mailbox across all our systems.

Note on delay after creating the mailbox
This process usually takes up to 90 minutes. In rare cases, it can take up to 3 hours. During this time frame, rejection may occur and requires no further action.

2. User verification set to Control Panel – Mailbox not present in Control Panel

If user verification is set to Control Panel but the mailbox does not exist there, emails will be rejected. To receive emails, the corresponding mailboxes must be created in the Control Panel.

3. User verification set to SMTP – Mailbox not present on the target server

If user verification is set to SMTP and emails are still rejected, the mailboxes likely do not exist on the target system. In this case, please check whether your target server accepts emails for the mailbox and whether there might be a typo in the email address.

What to do if the rejection persists?

If the rejection continues even after the mentioned waiting period, please check the following points:

• Which user verification is activated in the Control Panel?
• Is the affected mailbox present in the Control Panel?
• Does the target server accept emails for the affected mailbox?

For more information about user verification, please refer to the documentation portal:
- Set Primary Environment Settings