Query: What to do if you use an A record but can't handle mail

> 
> Gentlemen -
>         Apologies for intruding in this manner, but I have a query for which
> the usual sources don't seem to have an answer.
> 
> What is the collective wisdom on providing A records (for Internet access) but
> stopping mail access? There are a large number of machines here in University
> College Dublin which require Internet access but can't run a SMTP server
> (they're PC and the like). I want to ensure that anyone trying to send mail to
> them gets a prompt refusal -- what I plan to do to is provide a DNS entry
> like this:
> 
>         toaster.ucd.ie. IN      A       137.43.2.29
>         toaster.ucd.ie. IN      MX      undeliverable.ucd.ie.
> 
> The host undeliverable.ucd.ie doesn't exist, which should as far as I know
> return a prompt "can't deliver mail" message. So, is this how other people do
> it? Is this the right way? Is there a better way? Any and all suggestions will
> be gratefully received.
> 
> 
>  - Arthur Green
>    University College Dublin Computing Services
>    Tel: +353 1 706 2456  Fax: +353 1 283 7077  E-mail: arthur at midir.ucd.ie
> 

If the PC has no smtp server listening on TCP port 25 and you have
no MX record for it mailers trying to deliver mail will get
"Connection refused by ..."
which should be enough I guess.

----------                                                     ----------
Antonio_Blasco Bonito                          E-Mail: bonito at nis.garr.it
GARR - Network Information Service      c=it;a=garr;p=garr;o=nis;s=bonito
c/o CNUCE - Istituto del CNR                         Tel: +39 (50) 593246
Via S. Maria, 36                                    Telex: 500371 CNUCE I
56126 PISA   Italy                                   Fax: +39 (50) 904052
----------                                                     ----------