On Thu, 23 Oct 2003, Greg A. Woods wrote:
> > names are in mail.demon.net. Note also that it would be wrong to have
> > an MX for plum.csi.cam.ac.uk since there are no valid email addresses
> > @plum.csi.cam.ac.uk.
>
> That's wrong. There is always at least one valid mailbox address at
> every mail server that answers and speaks SMTP on port 25 (and it _must_
> be valid for both the host name of the mailer as well as for a domain
> expressed as a literal IP address).
You want Tony to have an MX for plum.csi.cam.ac.uk ?
Then people will start sending mail to @plum.csi.cam.ac.uk.
Not desirable, but stopping it is a battle he wont win.
He then retires plum from mail server duties, so has to make the
plum MX record point at another machine, say peach, otherwise
he wont receive that mail.
Since plum still has an MX record, at least some of these schemes
which only accept mail from machines with MX records will allow
mail from this machine even though Tony no longer wishes the machine
to be trusted as a mail server.
> There _should_ always be an MX for every domain name that is a host name
> of a mailer, and the target name of the MX should be the same domain
> name:
I thought that the point of an MX record was to allow you to tell
people that another machine handles mail to this host/domainname ?
If the host name of a mailer must be target of an MX you are
forbidding asymmetric setups with different boxes for incoming and
outgoing mail.
--
Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge
A.C.Aitchison@??? http://www.dpmms.cam.ac.uk/~werdna
