Outgoing emails from Outlook (Microsoft 365 Family) with custom domain are being rejected as spam

Markus_1981 0 Reputation points
2025-01-20T10:48:29.9466667+00:00

Hello,

My family is using Microsoft 365 Family in combination with our own domain.

We use email addresses in the format firstname@lastname.email.

Since Friday, we have been receiving a reply for many sent emails stating: "Your message couldn't be delivered because the recipient's email server (outside Office 365) suspected that your message was spam...."

The problem occurs with several family members (different accounts) and both via Outlook on Windows as well as via outlook.com.

Is this a general issue with Office 365? If so, when will it be fixed?

Or are there any configuration settings we need to adjust? e.g. DNS setting, etc.

Thanks & Regards,

Markus

Microsoft 365
Microsoft 365
Formerly Office 365, is a line of subscription services offered by Microsoft which adds to and includes the Microsoft Office product line.
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Outlook
Outlook
A family of Microsoft email and calendar products.
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  1. Joan Hua-MSFT 4,585 Reputation points Microsoft Vendor
    2025-01-21T02:18:36.28+00:00

    Hi @Markus_1981

    Welcome to our forum!

    What is your account? Outlook.com or something else?

    Does the issue occur recently on Outlook Desktop Client? Do you have any specific operation before the issue occurred? 

    According to your description, the issue of your concern is that your sent emails marked as spam.

    First, please be kindly to have a check for your domain Office 365 Anti-Spam IP Delist Portal.

    Also, it is suggested please kindly go to Domain to set up page from your Microsoft Admin center and check if TXT records are correctly updated and have no issue. If records do not update correctly or any error, kindly contact your local domain provider and update the record.

    • Micosoft365 portal > Admin center > Settings > Domain > select your affected domain and check DNS records.

    If all above works fine, could you please ask the recipients to add your domain into the safe list( as safe sender) to see if it helps.

    If not, you may want to refer to the article Remove blocked users from the Restricted entities page - Microsoft Defender for Office 365 | Microsoft Learn for more details.

    Hope it helps! 


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