Compu$erve RFC 1123 5.3.3 violation

Sat Nov 16 23:25:22 UTC 1996

This:

>   > $ host mailgate.compuserve.com
>   > mailgate.compuserve.com is a nickname for mx3.compuserve.com
>   > mx3.compuserve.com has address 149.174.206.135
>   > mx3.compuserve.com has address 149.174.177.136
>   > mx3.compuserve.com has address 149.174.217.133
>   > mx3.compuserve.com has address 149.174.217.137
>   > mx3.compuserve.com has address 149.174.217.136
>   > mx3.compuserve.com has address 149.174.217.135
>   > mx3.compuserve.com has address 149.174.177.134
>   > mx3.compuserve.com has address 149.174.177.133
>   > mx3.compuserve.com has address 149.174.206.137
>   > mx3.compuserve.com has address 149.174.206.136

...is NOT a variance from RFC1123 or any other specification.  It is
completely appropriate for a mail domain to be a CNAME pointing at a
handful of A's.  It's not ok to _advertise_ one of these, as for example
in an exported "From:" header, but there's no problem just from being
willing to accept mail sent to such a domain or to set up DNS in this
way.

> Make the DontExpandCnames option true in your /etc/sendmail.cf, and when
> customers start bitching that they can't send mail to CompuServe addresses,
> tell them that it is CIS's fault, and give them the CIS customer service
> number :)

Please don't do that.  CIS is committing some real sins against the RFCs
elsewhere, and since this isn't one of them it would muddy the waters if
we contrive to get them yelled at for it.