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Cisco Bug: CSCvt44551 - Request for ESA to check the mail header 'Sender:' and 'From:' to evaluate a SPF/SIDF: pra violation

Last Modified

May 15, 2020

Products (1)

  • Cisco Email Security Appliance

Known Affected Releases


Description (partial)


1. Our domain is
2. The allowed SMTP IPs for this domain are: X.X.X.X and X.X.Y.Y
3. the envelope sender is
4. the mail header Sender: --- not present ---
5. the mail header From: is
6. the mail was sent from Y.Y.Y.Y
7. The ESA does run the SPF/SIDF: pra check

result: FAIL,  Y.Y.Y.Y is not allowed to send mail for

The problem is, that Outlook does use the From: field to display the purported sender.
So you can _very_ easily bypass the SPF/SIDF: pra check!!!!!

Mail containing a mail header field 'Sender:' _and_ a mail header field 'From:' then the mail header field 'Sender:' does take precedence from the 'From:' field.
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Bug Details Include

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