Re: [Exim] Re: Underscore in domain is being rejected

On 2002-06-30 at 19:06 +0100, Matthew Byng-Maddick wrote:
> Be very careful with your wording. Underscores *ARE* legitimate in domain
> names. They are *NOT* legitimate in *host* names, and they are not
> legitimate as domain parts of email addresses.

Reference for illegitimacy in host names, please?

Nothing in Host Requirements that I've seen.

This:
RFC 2181 Clarifications to the DNS Specification
is a useful read.

Underscores are not valid in SMTP email domains. It's fairly silly to
use them for hostnames, in part because of this. But to the best of my
knowledge, no IETF Standard (or RFC in Standards Track) forbids use of
an underscore in a hostname.

> Windows is, therefore perfectly within its rights to generate underscore
> names, and it does (in the case of Active Directory). It's just not allowed
> to use them in email addresses.

Agreed (on the principles; I'm not qualified to comment upon what Active
Directory does).
--
"It's not a Y2K bug, it just has 1999 hardcoded in a bunch of places"