And while I'm ripping links from NtK:
Some enterprising cypherpunk type has written a CGI for
disguising messages in spam boilerplate.
That's right; "we strike at 23:55" comes out as "Dear Business person ; This letter was specially selected to be sent to you . If you no longer wish to receive ..." and several pages of similar verbiage. It should keep Echelon busy for
a while.