cname replace in mail address? [off-topic] (Re: Attn Ronald Klop)

[Doug Barton]

On 08/27/2010 01:03 AM, Ronald Klop wrote:
> offtopic, but why do some mailers replace a CNAME in a mail-address?
>
> root at sheeva2:/var/vmail# host klop.yi.org
> klop.yi.org CNAME thuis.klop.ws
> thuis.klop.ws A 212.123.145.58
>
> It is not the first time that I'm bitten by this, but I never understood
> it.

You've already received all the right answers but I figured I'd respond 
too since this is my area. Given that klop.yi.org is a CNAME, and that 
the target hostname (thuis.klop.ws) has no MX record, the fact that you 
receive any mail at all is a tribute to the robustness principle. :)

If you're going to receive mail at thuis.klop.ws then you should really 
have an MX record for it. See http://dougbarton.us/DNS/MX.html for more 
information if you need more information or references to the standards. 
The simplest way to solve your mail delivery problem is to have the 
@hostname refer to a canonical host (I.e., with an A and/or AAAA record) 
which also has an MX record. If you insist on using klop.yi.org the 
_best_ way to do that would be to duplicate those 2 records from 
thuis.klop.ws. By adding an MX to thuis you are more likely to get mail 
if klop.yi.org is a CNAME to it, even though it's still not "right."


hth,

Doug

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