Hello all,

I am dealing with a strange case where sending messages from my personal account (office365) to multiple recipients inside the same organization (Exchange on-premise infrastructure) it seems that this message is split into multiple copies (different network-id).

Example

Sender: user@office365.com

Recipient: user1@domain.com ; user2@domain.com

The message comes inside the organization in two instances with two distinct network message id. Only thing I can think of is a UTM from Sophos controlling the mail flow in a way (building queues as far as I am aware) but could this be case?

Any ideas are welcome, thanks.