On Thu, 19 Nov 1998, Schreckenbach, Jan wrote:
> sorry, I know that this topic was discussed in-depth. I read
> most of the messages about. What I don't understand is why underscores
> may be valid in dns.
They can't be according to the standards. There was some question about
whether they might be valid in MX records, but that was open to
interpertation and was due to a vagueness in the RFC. It is clearly the
intent that they are not allowed even in MX records.
> (I can turn off the check in /etc/named.boot) but
> never in email addresses.
Whether you can turn the check off for your version of bind is irrelevant.
I can produce things that are similar to email messages but violate the
standards with almost any email software. The range of behaviors of
software is NOT the definition of the standards.
If on a private network, you want things that look like DNS but allow _ in
hostnames, that is your business, and software might allow you do do that.
But once you connect your network to a public network, you have the
responsibility to follow the standards.
> I've often seen underscores in hostnames
Then those are misconfigured DNS servers, and technically, if they have
underscores in them they are NOT hostnames. They may be intended to serve
as hostnames, but that is not what they are.
> and so there are a lot of email addresses based on hostnames with
> underscores in it.
Well, those sites should get their names fixed.
> I really think there should be an option to use exim with these
> addresses ( e.g. in an environment with NT).
Just don't expect mail to and from the outside world to be reliable if you
do that. It will be much better if you rename the hosts in the local
environment so that they have valid hostnames.
> I there any possibility to have underscores in email addresses without
> changing the code?
I'll leave that for others to answer.
But let me beat the drum for RFCs and the standards process. The RFCs are
like a consitution, which you voluntarily accept. If you run a service on
port 25 on a visable host, then is should follow the SMTP RFCs. If you
talk to hosts to port 25 then you should follow the SMTP RFCs. What you
do an a private network or behind the scenes is your business, but if you
want those NT boxes to be on the net then you should give them proper
names or invite failures.
-j
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Jeffrey Goldberg +44 (0)1234 750 111 x 2826
Cranfield Computer Centre FAX 751 814
J.Goldberg@??? http://WWW.Cranfield.ac.uk/public/cc/cc047/
Relativism is the triumph of authority over truth, convention over justice.
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