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From: none <hzcnjkx656@tormails.com>
Newsgroups: comp.mail.sendmail
Subject: Re: sender rewrining advice
Date: Sun, 24 Mar 2024 00:59:40 +0100
Organization: A noiseless patient Spider
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> 
> My understanding is that the hash offers a modicum of security to 
> prevent (for some value) someone reversing your SRS mechanism and 
> sending messages to your server that your server would end up sending 
> back out as spam.  I think that it's mostly anti-abuse / anti-reply.
> 
> If I know your secret hash seed I could use that to generate an SRS that 
> your system would trust, reverse the SRS and pass the message on to the 
> intended destination as if it originated from your server.
> 

Hmmm, I don't really get this. My spf (and maybe even dkim) are still 
applied not?

If I am processing the message

test@gmail.com -> test@example.com forwarded to test@guerrillamail.com

then my host B (outgoing) will create a new envelope, something like:

SRS0=HHH=TT=example.org=test@example.com

Any receiving host will still check the same example.com spf, as if it 
would be a 'regular' envelope.