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Hello,
Please i need your help on this issue.
Recipient: ******@XXXX.com Sender: @XXX.XXX ServerIP: 52.98.178.242 Server: smtp.office365.com Header: Header size exceeds fixed maximum size Server response: 552-5.3.4 01JKSPHRJ9S1T5MSZZV6K09BBA ([@zendesk.com]): Rejected with MX smtp.office365.com - 552 Header size exceeds fixed maximum size The same happened to the recipient: ******@XXXX.com, ******@XXX.XXX, ******@XXXX.com
As the email is being sent from your custom email address: ******@XXX.XXX using your external email server, I will recommend reviewing what limits in attachments your server and end users have to avoid the rejections.
Hello, @John Peter
Just checking in to see if above information was helpful.
If the issue has been resolved, please mark the helpful replies as answers.
Best Wishes,
Alex Zhang
You are probably adding too many hops to the message flow. Or too many custom headers etc...
You cant raise the header size, instead troubleshoot it from the mail flow side and look to reduce the hops or whatever is filling up that header.
I agree with Andy David's idea. Raising the header size limit is not supported at this time. Consider reducing the number of recipients and sending them in groups. Simplify the email subject or remove non-essential information from the header.
Is there any update on this thread? If the issue has been resolved, please mark the helpful replies as answers, this will make answer searching in the forum easier and be beneficial to other community members as well. Thanks for your understanding.
Hello Andy David - MVP and Tianyi Chang (Shanghai Wicresoft Co Ltd)
Thank you for your reply.
How do we check as per the email/headers
Hi @John Peter
We can't view the header size directly, but we can view it with the help of .txt. Copy the header information to a .txt file, and then view the file size through the properties that is the header size.
If you are using outlook, you can double click on the email and find the header through File - Properties.
If you use owa, you can go through more and see the view message details.
Hope it helps!