Question regarding symbols in name resolution

Kevin Darcy kcd at daimlerchrysler.com
Thu Apr 19 22:27:59 UTC 2001


Well, first of all, the part of an email address that precedes the @ is not a
DNS name. Underscores are legal in the *mailbox* part of an SMTP address. The
company abc folks apparently don't understand the composition of an
SMTP address.

More generally, underscores are only illegal in "hostnames". Not everything in
DNS is necessarily something that would be used in a hostname. SRV records, for
instance, have owner names with underscores in them; in fact, this was done
deliberately to distinguish them from hostnames.


- Kevin

Patrick McAllister wrote:

> I apologize for what is not doubt a very basic question. I think I already
> know the answer to this but would definitely like a second opinion.
>
> As I understand it, certain symbols are "forbidden" in DNS, one of which is
> the underscore. My problem is this, I have a client who has a mail server
> they have named companyxyz_smtp at xyz.com. They actually seem to get mail fine
> from everyone except one organization. This one organization, say company
> abc, claims they cannot send mail to company_xyz because of the underscore.
>
> Is an underscore indeed a "forbidden" character? If so how is it no one
> except company abc seems to be having these issues.
>
> Thanks in advance, flame away if need be to me at tomservo at erols.com!





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