E-mail is now reproducing in the wild?

[VirginSnow at vfemail.net]

VirginSnow at vfemail.net writes:

> The duplicate messages that I've analyzed all appear to originate in
> webmail interfaces.  Some duplicates (those from Yahoo, it seems) have
> identical Message-ID headers, but other duplicate messages have
> different Message-IDs.

The duplicate messages from @gmail and @yahoo addresses all appear to
have the same Message-ID as their copies BUT, somehow, the MIME
boundary string in the duplicate message differs from the original.
Any idea how that can be?