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451 4.4.4 no mail enabled subscriptions

Anonymous
2024-04-10T14:23:41+00:00

Our ERP system sends emails through SendGrid to our internal user email accounts hosted on Microsoft 365. This has been working for several years. Two days ago, M365 started bouncing some of those emails. The error message Microsoft presents as the reason for the bounce is:

451 4.4.4 Mail received as unauthenticated, incoming to a recipient domain configured in a hosted tenant which has no mail-enabled subscriptions. ATTR5 

The message is then followed by some text that looks like the server that bounced the message and a timestamp. Something like this:

[SJ5PEPF000001C9.namprd05.prod.outlook.com 2024-04-10T08:01:25.289Z 08DC565EF8D77C86]

They all appear to be produced by namprd02, namprd03, namprd04, namprd05, or namprd21.

We have over a hundred email enabled users and and a couple of dozen legit receivers have been bounced. SendGrid stops trying after a bounce until the bounce is manually cleared. I have cleared the bounces and most times it works normally after that, but sometimes additional bounces for the same recipients results.

This does not appear to be a blip, but a continuing problem. Any thoughts?

Microsoft 365 and Office | Subscription, account, billing | For business | Other

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  1. Anonymous
    2024-04-10T16:35:20+00:00

    Hi BXM IT Manager,

    Good day.

    Thank you for connecting with us on Microsoft community.

    According to the description, I have consulted with my team members, I would like to share more specific information with you, in order of your certain situation, several things can be checked by backend side technical support team such if something wrong in your tenant organization from server level etc..

    As an Office 365 global admin may need to contact again our Office 365 support team on the back-end side via an open service request so they can diagnose this specific scenario through some more technical resources, they maybe collecting some different logs information for further diagnosis. They can escalate this issue to the next level of the support team after collecting logs if it is required.

    Since we forum moderators have limited permissions and access resources, due to this reason we are unable to collect certain detailed information in the public forum for data privacy. After diagnosing the scenario, our technical support team can provide possible information from their end.

    If there is any known issue, our technical support team can provide from their backend resources.

    For this standard process, here's the official document for the global admin: Get support - Microsoft 365 admin | Microsoft Learn (Online Option).

    End users need to contact Office 365 global admin person in their organization to do some standard process and to connect with frontline technical support team.

    Important note: If any organization's Office 365 Business/Business/Education subscription is from a syndicated partner or reseller, and if the global admin can't open the service request on their end, they may need to contact the reseller's support provider so they can help the global admin to open the service request on their end. after the Office 365 support team will involve in the created service request.

    Your cooperation precious time is highly appreciated.

    Sincerely

    Vaidya Darpan

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  2. Anonymous
    2024-05-06T16:44:11+00:00

    Did you get a resolution for this issue? If so, please share what the issue is and how it was resolved.

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