Subject: [dispatch] SMTP Code for Undesirable Messages

From: "Brotman, Alex" <[email-masked]>
Date: Fri, 17 Dec 2021 17:04:46 +0000

Hello,

I've been wondering if it may be beneficial for a mailbox provider to be able to signal back to the sender that the message is being accepted, but is undesirable based on some criteria.  The idea would be that a provider may evaluate some characteristics of the message, and before issuing a "250 Ok" have already determined the message would be routed to the spam folder.  Something as simple as:

255 Ok - Routing to spam folder

This would likely need some "Security Considerations" section about how informing a malicious entity may be undesirable.  I'm willing to write this up as a proposed draft, though I'm not entirely sure where to direct that draft.  Thank you for any advice you could provide.

--
Alex Brotman
Sr. Engineer, Anti-Abuse & Messaging Policy
Comcast