Sophos Data Control Rule 552 5.6.0 Headers too large (32768 max)

Your headers aren’t the problem. No header will ever get to 32mb. You must have attachments to make it report an error like that. A 32mb email is quite big.

This is about user education. In my view, the sender should be using OneDrive to share files, not email. Otherwise your mailboxes will fill up way too quickly. Email should be for messages, not file transfers. However, if you wanted to allow this you simply need to increase the maximum email size is office 365 to 50mb, or whatever you need.

This link may help: community.sophos.com/.../data-control-inspect-modify-header

Your headers aren’t the problem. No header will ever get to 32mb. You must have attachments to make it report an error like that. A 32mb email is quite big.

This is about user education. In my view, the sender should be using OneDrive to share files, not email. Otherwise your mailboxes will fill up way too quickly. Email should be for messages, not file transfers. However, if you wanted to allow this you simply need to increase the maximum email size is office 365 to 50mb, or whatever you need.

This link may help: community.sophos.com/.../data-control-inspect-modify-header

Hi, 

Thanks for the feedback, maybe I expressed myself wrong. It's not about the total size of the email, but about the headersize.

• Message header size limits: Specifies the maximum size of all message header fields in a message. The size of the message body or attachments isn't considered. Because the header fields are plain text, the size of the header is determined by the number of characters in each header field and by the total number of header fields. Each text character consumes 1 byte.

According to the text the Headersize exceeds the 32768 characters this must be a Headersize of 32KB in total.

We have some Mail Flow Rues attaching Signatures for example and Microsoft ist adding a lot of stuff in the Header.

Thank you 

Sebastian