[Maybe OT] - RFC compliance checking at session

Glenn Steen glenn.steen at gmail.com
Fri Feb 29 21:44:58 GMT 2008

On 29/02/2008, Matt Kettler <mkettler at evi-inc.com> wrote:
> Hostmaster wrote:
>  > Hi All,
>  >
>  > I would like to illicit some opinions from you other MailScanner using
>  > MX-administrators.
> Pretty much all your opinions here are valid, except:
>   > and the IP does not accept return SMTP – indicating that
>  > it's probably a web server and not an MTA itself.
> I find that conclusion irrational. Why wouldn't it be an MTA?
>  Anyone large enough to have separate MX (inbound) and smarthost (outbound)
>  servers should *NOT* be accepting inbound SMTP connections to their smarthost
>  servers from the outside world. Only their internal network should be able to
>  SMTP to the smarthost.
>  There's no reason to allow it, so best practice would suggest you should close
>  that off at the firewall. Any legitimate mail delivery attempts will go to the
>  MX servers. Therefore any attempts to connect to port 25 on the SmartHost from
>  the outside are either hackers, scans, or random pokes and prods at parts of
>  your network nobody on the outside belongs in.
>  I think it's a pretty far jump to assume that any system that generates SMTP but
>  doesn't accept inbound from you can't be an MTA. It's quite possible it is an
>  MTA, but you're not authorized to try to queue mail there and are firewalled out.
I'm not going to disagree (much:-) with you today/tonight Matt (not
sober enough, and I need be very sharp when doing that:-):-), but what
about all that stuff ... domain litterals etc... all there to
facilitate bouncing when there is no DNS etc. Kind of implies that all
SMTP sendersare supposed to be able to be receivers too, now don't it?
Or maybe I'm in delirium tremens and that is just a figment of that state:-):-)

-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se

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