hmmm, mail coming from such sources usually contains the program
identification string that wrote the mail in the first place if memory
serves.  Why not reject any email from a non-compliant mta attaching a
message onto the rejected email stating x is a non-compliant mail
transport agent and messages sent will not be recieved or read at this
domain.



On 7 Oct 2002, Heimo Claasen wrote:

> Yes, there is an problem with an increasing number of mail troubles.
> No, this is not a Fetchpop problem: I see it with all sorts of mail
> transport agents (MTAs) not only under Linux.
>
> My suspicion for the reasons go towards a specific recent version of
> the Outhouse Excremental Exploder, perhaps even only the Mac version of
> it, in combination of the send-MTA used therewith; I think it may go
> like this:
>
> While the mail composer forcibly changes/remaps all 8-bit characters
> in a charset used, it doesn't do so with an imported/pasted signature
> or likewise element.  The send-MTA though then chops _all_ 8-bit chars
> in an - as illegal as erronous and wrong - manner[*] to make it 7-bit
> "compliant". This is especially critical when the 8th bit in the 128 to
> 159 (dec) range of charsets is cut; the result is that illegal, 7-bit
> "low ASCII" chars are created with these remains, and sent.
>
> However, all decently behaving, and truely RFC-compliant MTAs -
> (a.) are 8-bit-transparent, i.e., don't change/eat/suppress 8-bit chars,
> as MS void professors do;
> (b.) rely on some combination of "low-ASCII" (dec 0 to 31) chars for
> control functions;
> (c.) rely on the RFCs and other "industry"-wide conventions (to which
> indeed everybody keeps, except MS) that such low-ASCII chars are not to
> be included in a mail "body".  (This is the whole point, BTW, of having
> UU- or Base-64 encoded "attachments" at all, in order to pack and
> transport binary data like program code or images through eMail.)
>
> So more and more of the decent, standards-complying MTAs, well-behaving
> over the years, will get into trouble.
> (BTW, you wouldn't see the culprit - except with capturing the complete
> packet stream -because the receiving MTA precisely hangs at that point
> and cannot print it.)
>
> The way to avoid this, besides of not using that crooked gear in the
> first hand, would be to have all SMTP servers to screen mail bodies;
> which they do not, presently, as they are nicely behaving and rely on
> standards.
>
> // Heimo Claasen // <hammer at revobild dot net> // Brussels 2002-10-07
> The WebPlace of ReRead - and much to read  ==>  http://www.revobild.net
>
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