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A SmarterMail customer of ours received a phishing message with the "From:" address matching a co-worker at their domain (ex. From: firstname.lastname@example.org, To: email@example.com).
We have "Enable domain's SMTP auth setting for local deliveries" checked so if the "MAIL FROM:" is a local domain, SMTP auth is required. The message came through because in the SMTP session the "MAIL FROM:" was a non-local email address (ex. firstname.lastname@example.org).
How do you stop messages where the "MAIL FROM:" does not match the message header "From"?