Long delay for sending emails in China (On-prem > EOL)

Harry Cheng 0 Reputation points

Our Beijing office reported this problem:

When an on-prem user sends email with >30MB file to an EOL user, EOL user only will receive it after >12 hours (sometimes is ~24 hours). Is there a way to fix it?

Pls note that, above issue impacts to all Beijing's on-prem users and EOL users, and it seems only happened in China offices (so far no other offices outside China report same problem).


Harry Cheng

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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  1. Aholic Liang-MSFT 9,171 Reputation points Microsoft Vendor

    Hi @ Harry Cheng,

    Using the Message Header Analysis tool to analyze the message headers of a test email can help us better locate which step the current message is lagging at.

    We can see the length of time each process takes in the delay column under "Received headers":


    Message header analysis tool:Message Header Analyzer (mha.azurewebsites.net)

    You can view message headers in the following ways:

    Outlook client:

    1.    Open the message.

    2.    On the File tab, click Properties in the Info area.

    Or, click the Dialog Box Launcher in the lower-right corner of the Tags group on the Ribbon.

    3.    In the Properties dialog box, locate the message headers in the Internet headers area.


    Right-click the email, click View and select View Message Details.

    In addition, maybe you can share the screenshot after removing all private information, such as the domain name and IP, so that we can better analyze the content.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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