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[Tadrill] Compilation of Error Messages for Delivery Status

This article is based on the product specifications as of July 2026.
Depending on Tadrill's Training Emails delivery method, click on the displayed Error message item to check the solution.

※ If an Error not listed below is displayed, or if the issue does not improve, please note the following Info and Contact Us at HENNGE One Technical Support.

  • Target Training name and Training Start date and time
  • Target users
  • Error message

Table of Contents

Training Emails delivery method: SMTP delivery

550 5.1.1／NoSuchUser／The email account that you tried to reach does not exist.+

The recipient's mailbox does not exist, or the email address is incorrect.
Please check the Settings on the recipient's side.

550 5.2.1+

The mailbox exists but is Disabled or not accepting messages.
Please check the Settings on the recipient's side.

550 5.2.2+

The mailbox has exceeded its storage limit.
Please check the Settings on the recipient's side.

550 5.4.1 Recipient address rejected: Access denied+

The receiving email system Denied delivery before it was completed.
This may occur when the recipient account is not Enabled or has no license assigned, when the Domain has not been Authorized, or when delivery is blocked by mail flow rules.
Please check the Settings on the recipient's side.

Training Emails delivery method: DMI delivery (Microsoft 365)

MailboxNotEnabledForRESTAPI+

Microsoft Graph cannot access the mailbox.
The mailbox may be inactive, soft-deleted, hosted in an on-premises environment, or may not be a valid Exchange Online mailbox.
Please check the Settings on the recipient's side.

Authorization_RequestDenied／Forbidden／403+

Access to Microsoft Graph has been Denied.
The required permissions for the DMI Integrations Settings may be insufficient, or admin consent may not have been granted.
Tadrill DMI needs to be reconfigured, so please Contact Us at HENNGE One Technical Support.

ResourceNotFound／Request_ResourceNotFound／404+

The Target users or mailbox could not be found.
Please check the Settings on the recipient's side.

ErrorQuotaExceeded／Insufficient Storage／507+

The recipient's mailbox has exceeded its storage limit, and the Training Emails cannot be saved (received).
Please check the Settings on the recipient's side.

Training Email Delivery Method: DMI Delivery (Google Workspace)

invalid_grant: user likely does not exist or is suspended+

The user may not exist or the account may have been suspended.
Please check the Settings on the recipient's side.

access_denied: client authorization has been revoked+

The client's authorization permission has been revoked.
Tadrill DMI will need to be reconfigured. Please Contact Us at HENNGE One Technical Support.

mail service not enabled+

Gmail is not Enabled for the Target users.
Please check the Settings on the recipient's side.

Translation Disclaimer

This article has been automatically translated from the original Japanese version for your convenience.
While we strive to ensure accuracy, we cannot guarantee its reliability or completeness.

In the event of any discrepancies or questions regarding the content, the official Japanese version shall prevail.