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Re: [Bug-mailfromd] srs (sender rewrite)


> >>
> >>> Do you have any experience implementing srs (sender rewrites)
> >>
> >> Personally I have never tried it, but I don't see any difficutlies
> >> in doing so.
> >
> > ...
> >
> > I prefer to have it like this
> > SRS0=HHH=TT=b.com=testing@xxxxx
> > SRS0=HHH=TT=c.com=testing@xxxxx
> 
> Actually SRS says the envelope from of the forwarded mail should be
> SRS0=HHH=TT=random.com=random@xxxxx and if the original sender was an SRS
> address also then it should start with SRS1.
> https://en.wikipedia.org/wiki/Sender_Rewriting_Scheme
> 
> If the resulting address is longer than 64 characters Microsoft uses a
> different format like below. https://learn.microsoft.com/en-us/microsoft-
> 365/troubleshoot/antispam/sender-rewriting-scheme
> 
> bounces+SRS=<Hash>=<Timestamp>@<Default Accepted Domain>
> 
> In the end SRS is a form of variable envelope return path (VERP) that adds a
> hash and timestamp, and without the formatted hash and timestamp you could
> just format it any way you like. The question is what to do if that mail
> bounces back. If you are willing to just discard it than it does not matter,
> if you want to process and somehow inform the forwarder or the original
> sender, than you need to check to make sure it's hash is correct and is not
> a fake address, etc.
> 

How would you decide when to re-write the sender and when not?