MS Exchange server corrupting PGP-MIME emails

Werner Koch wk at
Mon Oct 31 11:36:53 CET 2011

On Sat, 29 Oct 2011 14:47, peter at said:

> So I guess I should rephrase my comment as a request: when this behaviour is
> fixed, please fix it for mangling in general and not just this specific PGP/MIME
> and S/MIME case :).

You need to know that Exchange is not an RFC822 application but an MAPI
application (based on X.400).  Exchange/Outlook uses MAPI for its data
structures and to convey messages to recipients with an X.400 address
(ie. other Exchange users in the the domain).  Rfc822 addresses are
merely properties of the MAPI message and used if the message needs to
be send via SMTP; this is done by a transport provider which constructs
a proper MIME message out of the MAPI message.  Obviously there are some
kludges in the system to allow sending of signed messages by taking
great care not to modify the content.  This is not documented but I did
some experiments to see how it can be used to receive and send

AFAIK, Microsoft tries to move away from MAPI - this will be a long
process.  It seems OL2010 supports new interfaces to allow applications
to use these kludges - however I only briefly looked at it.



Die Gedanken sind frei.  Ausnahmen regelt ein Bundesgesetz.

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