[Mediawiki-l] How to open the letters of Brion?

[Chris W]

The attachments I think you are referring to are digital
signatures for the content of the message and don't carry any
human readable information.  The signature can be used to verify
that it really was Brion that sent the message, and that the
message has not been tampered with enroute.  AFAICT Outlook
Express is not capable of verifying these signatures.