[Spambayes] illegal header tanks SpamBayes

[Tim Peters]

[Skip]
>     Bobby> I believe I already reported this before, but SpamBayes
>     (v3 of
>     Bobby> the Outlook installer) does not recognize the
>     following SMTP
>     Bobby> header, and refuses to process the email:
>     Bobby>      X-MS-Mail-Gibberish
>
>     Bobby> I am seeing an increasing number of these, so it appears
>     that the
>     Bobby> spammers are figuring out that spam-processors
>     are bombing on
>     Bobby> illegal headers...

> Funny, I don't have a single mail message anywhere (except the one I'm
> replying to) which contains that string.  Could it be that Outlook is
> adding it?

Yes, the Outlook addin *sometimes* generates an X-MS-Mail-Gibberish header,
to disguise that Outlook itself can produce an invalid (non-RFC compliant)
header section.  See msgstore.py in the Outlook2000 directory:

        # Mail delivered via the Exchange Internet Mail MTA may have
        # gibberish at the start of the headers - fix this.
        elif headers.startswith("Microsoft Mail"):
            headers = "X-MS-Mail-Gibberish: " + headers

The Python email package accepts any RFC-compliant string of characters as a
header tag.  We made up "X-MS-Mail-Gibberish" out of thin air, and it's not
the cause of Bobby's problem (although that such msgs are delivered by an
Exchange server may be part of a problem).