On 2002-03-30 at 23:13 +0100, Tony Earnshaw wrote:
> I don't agree.
The RFCs don't agree with you. They _specifically_ lay responsibility.
> Both send/accept the 7 bit characters that hermes.mail.nl.demon.net
> accepts. When www.dagbladet.basefarm.net sends 8 bit characters, only
> ØøÆæÅå are snuffed, the rest comes through.
Dude, please check which machines you're referring to. Hermes does run
Exim.
$ dnsmx nl.demon.net
10 hermes.mail.nl.demon.net
20 relay-2.mail.nl.demon.net
Staff mailhub. Note that checking DNS MX for @demon.nl is not going to
give you the customer mail-system, since @demon.nl is for
customer-facing addresses. Things like <support@???>.
> If hermes.mail.nl.demon.net had have been running Exim or Sendmail in
> 8bitmime accept mode, the 8bitmime would have been accepted.
>
> That's the whole point.
If an MTA has accepted a mail, knowing that it's promised that it will
handle 8-bit data, then if it talks to a second MTA which does not
promise 8-bit support, that first MTA is responsible for checking if the
mail is not 7-bit clean and, if so, performing the appropriate
conversion. In the case of RFC 1652, which is the only current method
that I know of, and the one which you cite, this means MIME conversion.
Which is horrid. And not done by Exim. So by default, Exim doesn't
advertise 8BITMIME. If you choose to advertise 8BITMIME when you _know_
that the subsequent mailpath is 8-bit clean, that's not going to cause
problems.
If you choose to enable it anyway ... well, that's what the original
poster was asking about. When informed of a major source of problems,
he wisely chose to avoid the way of recklessness.
When Demon's mailsystems move to Exim, they _still_ won't advertise
8BITMIME, since we don't know what our customers run and Exim doesn't
convert. So the sending MTA will _still_ have to convert. The only
difference there will be that if the sending MTA is broken and the
recipient happens to be 8-bit clean, the sending MTA would get away with
being broken.
Now, if you want to change any of this, consider ways to persuade Philip
Hazel that protocol conversion support should be added to Exim, so that
it can at least arrange for another program to do conversion, when
necessary. Without knowing what the performance impact of that would
be, neither I nor my employers can make any assurance as to whether or
not we'd use that. But you could certainly use it on your mailsystem,
and persuade others to do so.
Start finding out which beers Mr Hazel is particularly fond of. :^)
--
"Being right too soon is socially unacceptable." -- Robert Heinlein
