[ALUG] Re: MX/Zone/DNS question

[cl at isbd.net]

On Fri, Jan 26, 2007 at 09:57:44AM +0000, Brett Parker wrote:
> On Fri, Jan 26, 2007 at 09:22:40AM +0000, MJ Ray wrote:
> > cl at isbd.net wrote: [...]
> > > I have Postfix on my home system (for sending mail).  If I want it to
> > > receive mail as well what do I need to do to the zone file[s]?
> > 
> > Short answer: it depends how your zone and Postfix are configured.
> > 
> > > At BSNet (where isbd.net has its zone file) will the CNAME entry I
> > > already have mean that mail for xxx at home.isbd.net will get sent on or
> > > do the MX records for isbd.net catch home.isbd.net mail as well?
> > 
> > More likely the first than the second, but I seem to recall that some
> > buggy mailservers handled CNAME badly.
> 
> Actually not buggy behaviour - an MX should always point to an A record
> (part of the spec, IIRC), and hysterically, an A record was checked for,
> now the order is MX -> A -> undefined evilness!
> 
... but that really doesn't answer my question.  If there's an MX
record (or MX records actually) for isbd.net does that have any
relevance to mail for home.isbd.net?  If it *doesn't* have any effect
then what happens to mail for home.isbd.net - will the CNAME entry
have any effect or will the mail just get rejected as having a
non-existent destination?

> > > If home.isbd.net mail *is* sent on to my home machine do I need to do
> > > anything to the zone file there for it to accept the mail or will
> > > having Postfix listening on port 25 be all that's needed?
> > 
> > Andrew Savory recently did something similar.  See
> > http://www.andrewsavory.com/blog/archives/001257.html
> > (but Googlemail really does not rock).
> 
> Opinion, not fact (I have never and never intend to use Google mail, so
> I can not say wether it rocks or not - but I'd rather my mail wasn't
> indexed by Google, TYVM).
> 
Not to mention that the above blog only talks about how to set up
Postfix which I basically know anyway.  What I want to know is whether
I *have* to have MX and/or A records in my home machine's zone file or
will things get there as a result of the CNAME record in isbd.net's
zone file.

-- 
Chris Green (chris at halon.org.uk)