Hi,
Bespoke software sends emails via SMTP through an O365 mailbox to a client's mailbox. Up until a week or so ago in the header info the originating IP was our server, but there have been a number of examples recently which have taken up a 10.x.x.x address on the MS network. When this happens, the 'from' identity is also amended to the account info of the O365 account rather than the identity set in the bespoke application which differs slightly.
I'm wondering if anyone has any ideas why this could be? I've requested mail server logs via our relevant department but it could be a while before they get back to me.
One theory i had was that the email could not be immediately sent to the recipient and so was pooled in O365 then the subsequent attempt to send it meant that the originating server info became that of the O365 identity and MS network..
Has anyone encountered anything like this before?
