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We have a Mailscanner, which scans incoming and outgoing mails and add a small disclaimer (Mail was checked for Viruses... bla bla bla).

So far i can add a disclaimer without signing the mail, or sign emails without adding the disclaimer. Is there a way if if sign mails with an certificate, to still be able to add this disclaimer?

Thanks

Steve

fips123
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1 Answers1

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If your email is S/MIME signed, you cannot add a disclaimer after signing the message. Adding a disclaimer after signing the message either invalidates the signature (i.e., the signature no longer validates) or the message is no longer a valid S/MIME message. One possible solution would be that the disclaimer service extracts the signed message and adds it as an attached message (content type message/rfc822) to a new message with the disclaimer. The same problem happens when using PGP/MIME signing since this is kind of similar to S/MIME signing. If you sign a message with PGP/INLINE, then you can add additional parts since PGP/INLINE signed individual message parts. The resulting message however is partly signed since the disclaimer is not signed so it's up to the client how to handle partly signed messages.

martijnbrinkers
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