RE: Demon Email - A firewall is NOT the answer

["Roger" <roger@xxxxxxx>]

What about putting Mercury Mail in between Exchange and Demon? Can be set
to
take mail as a client, and re-serve it locally. AFAIK Mercury can be
relay
proofed, and Exchange would still be talking to a SMTP or POP3 server.

Roger Shingler

>
> Rob,
> 
> A firewall won't help, unless it also does mail relaying for you.
> 
> Port 25 needs to be open to receive email full stop. The 
> relaying issue is that port 25 should only accept email 
> either TO or FROM one of your domains. (ie - should only 
> accept email to one of your users or from one of your users - 
> the thing that Demon'
> s trying to block is your email server accepting email from 
> one third-party, and passing it on to another third-party.)
> 
> Commercial firewalls (like firewall 1) will accept plugins 
> that handle mail relaying for you, but the "turnkey Linux 
> ones" won't, AFAIK.
> 
> You need some mail relay. Linux SENDMAIL is probably the best 
> solution.
> 
> Regards,
> 
> Mark
> 
> -----Original Message-----
> From: Rob Mouser [mailto:rmouser@xxxxxxx]
> Sent: 13 June 2002 13:43
> To: Ukha (E-mail)
> Subject: [ukha_d] Demon Email
> 
> 
> Hi 
> 
> This is a little 'wide' but I feel it is relevant to us HA people.
We
> have a Demon Web account here and was infact on the verge of 
> setting one
> up for home (Fixed IP etc, ISDN, fixed cost etc.....However don't
post
> on this as its not the subject!) HOWEVER we have just had 
> external email
> banned by Demons Abuse Team due to our MS Exchange Server 
> v5.0 (Part of
> SBS Ver4.0)beeing venerable to email spammers using relay. I've
spoken
> to Demon and done some research and it appears that Exchange
Ver5.0
> cannot be protected against relay attacks! Only Ver5.5 has 
> sufficient t
> functionality to block relay use.
> 
> OK so we cannot upgrade to 5.5 (Various issues with compatibility
with
> some bespoke software supplied by another company.) (Or in effect
SBS
> v4.5) at this precise moment and so the only option is to add 
> a firewall
> to the network (25 users) anyone got any recommendations that will
do
> the trick? As long as Demon can telnet in and get refused 
> they will open
> us back up.
> 
> Yours bemused and confused.........
> 
> Many Thanks
> Rob
> Rob Mouser
> rmouser@xxxxxxx
> rob@xxxxxxx
> 
> 
> 
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