The above referenced message contained a virus, as an attachment, which was deleted and replaced by a warning message by the time it reached me.
Response
Content-type: TEXT/PLAIN; NAME=alert.txt Content-description: original attachment was replaced Content-disposition: attachment; filename=alert.txt
Attachment converted: MacHD1:alert.txt (TEXT/MSWD) (00118476)
I've been getting a ton of such "returned" messages.