Underscores in Host Names

[Kevin Darcy]

R.D. wrote:

>Hello all.
>We have a client containing an underscore in the email address domain
>name.  
>
Please define exactly what you mean by that. Do you mean the *owner* of 
the MX record has an underscore in it, or do you mean that the MX 
*target* has an underscore in it? The target shouldn't have an 
underscore in it, since it is considered to be a "hostname" and 
underscores in "hostname"s is forbidden by RFC 952. If it's the MX 
*owner* that has an underscore in it, then I think that's allowable 
under the standards, and your email software is being too picky.

                                                                         
                                                - Kevin