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Spam detection is run locally on the receiving mail server, and adds the result information to the email as the "X-something" header fields you are referring to
by arghwhat 6y ago
Spam detection is run locally on the receiving mail server, and adds the result information to the email as the "X-something" header fields you are referring to as part of the receive pipeline. See e.g. rspamd.
Should you forward the email with these header fields intact, then all it does is reveal a bit about your mail providers' infrastructure, which is already entirely public information.
- jakobdabo 6y agoI've seen small parts of my email body in the "X-something" headers inserted there by the anti-spam service. I can try to find an example later when I get to my desktop.
- arghwhat 6y agoI don't have memory of such behavior, but even then, this is in your receive pipeline, reading plain-text, publicly readable email meant for you and appending something to its plain-text, publicly readable header meant for you, all in order for the server to present this information to you/your mail agent. I don't see why any of this would lead to any amount of concern, but feel free to present the header field you refer to.