Re: Digital Certificate "There are problems with the signature"


Here is the original question from
http://groups.google.ca/group/microsoft.public.security

"
Dear All,

We are testing out Digital Certificates as a prelude to Secure
Messaging
with some of our Clients.


We obtained individual certificates for ourselves (as there is not many
of
us) but started our Client on a Business account with a CA.


After setting up one of their users we notice that most times their
email is
fine, but other times instead of the usual "rosette" there is a red
line and
the statement "There are problems with the signature. Click the
signature
button for details."


The message in the Security Properties is "Error: The message contents
may
have been altered. Signed by sa@<client domain here>.com using RSA/SHA1
at
15:05:47 16/08/2006."


As we use an external mail filter (so all our mail is scanned in
transit) we
believe that the scanning by our mail filter is causing the Digital
Certificate to detect a modification (or attempt) and hence the error.


My questions are:


1) Is the above assumption correct, and this is normal?


2) Is there anything that can be done to elimiate this (if caused by an

external mail scanner perhaps not)


3)If we move to Secure Messaging where the email is encrypted and hence

cannot be scanned by our mail filter, should I presume that the above
error
will not appear and that all will be OK (at least as much as it should
be)?


thanks "


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