Re: [dispatch] SMTP Code for Undesirable Messages

[Anton Tveretin <[e-mail]>]

Hello Alex,

I think it is sometimes a good idea. But the problem is that spammers sometimes use this kind of feedback to check for valid addresses. For this reason, some implementers would avoid this feedback. Also, a check for spam need not complete immediately. The incoming message might be bounced later.

Sincerely yours,

Anton

 

--

Date: Fri, 17 Dec 2021 17:04:46 +0000
From: "Brotman, Alex" <[e-mail]>
To: "[e-mail]" <[e-mail]>
Subject: [dispatch] SMTP Code for Undesirable Messages
Message-ID:
        <[e-mail]>
        
Content-Type: text/plain; charset="us-ascii"

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