Re: Underscores in host names

[Tony Finch <dot () dotat at>]

On Thu, 19 May 2005, Roger Marquis wrote:
> As it should.  I wish it would also return a null for hostnames
> containing sequential non-alphanumerics (--, ---, __, ___, ...).

It is possible to reject multiple dots, both in theory and in practice (in
fact it's a useful for spotting certain kinds of spamware that generates
bogus HELO domains).

You can't reject double hyphens because they are permitted by the syntax
and used by IDN, for example.

Tony.
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