Hi
I've been playing around with domainkeys and I've turned up the
following problem: as part of my normal mail processing, I add some
headers (and may remove some as well, especially at SMTP transport
time. This has the potential to break the DK signature. I do this
to prevent spamd reports and other internal processing stuff from
being leaked out. I also add an X-virus-scanned type header.
The X-virus-scanned header can be added above the Domainkey-signature
because it's added by an ACL. But the other headers added at
delivery time are added by the transport and they break the DK
signature. Also, if someone has delivered a mail that has any of
my removed headers:
GLOBAL_HEADERS_REMOVE= Delivered-To :\
Envlope-To :\
X-Spam-Score :\
X-Spam-Flag :\
X-Spam-Report :\
return-path
That will break the signature too, especially if it came in with a
spam score/report. I'm not too concerned about Delivered-To,
Envlope-To and return-path.
Also users popping their mail will not be able verify the DK signature
because of locally added headers.
It would be nice for routers to be able to specify the location of
headers they add, and to have a
"Dont_Mess_With_Headers_Below_Domainkey-signature" option.
Any ideas or suggestions other than "don't mess with the headers"?
Ian
--
Ian Freislich
