EXCHANGE: Reverse DNS

I have found out why I am getting bounced emails. An ISP subscribes to
SORBS which has a database of spammers, etc. Our IP Address ( supposedly
STATIC ) is actually in a Dynamic range of 220.240.220.0 to 220.240.223.255
which is blocked by http://www.dnsbl.au.sorbs.net/ .

Requests can be made to have your IP Address removed from the blocked list
(see above URL) which I have now done but they are asking:
NOTE to Endusers: "Suitable rDNS" means there should be a PTR record that
points to your MX record and visa versa.

Can somebody please advise me what/how to do in Exchange. I have my MX
record in place.

TIA

Malcolm

 

It appears this must be done by the ISP.

I have sent them a message.

Thanks....


Malcolm

 

Actually, what is being asked of you needs to be
configured by whoever is managing your Domain's DNS
records... which may or may not be your ISP.

Tony Su

 

Hi Tony

I'm no longer on site.

I did a bit of sniffing around in Exchange System Manager
and found a checkbox that said something like "activate
reverse DNS" which I did.

Is this correct?

DNS(1) and (2) are set to our ISP in CEICW.

Malcolm

 

I had also installed KB8314?? and SP1 this afternoon. OWA
appears to DL additional files (long time modem activity)
before allowing login and then also requires to enter full
Domain\Username at login..

(Used RWW to check what I had done). I have now unticked
"Perform reverse DNS lookup on incoming messages" However,
using Ex Sys Mgr, I did drill down to SMTP...Delivery and
added my ISPs mail server to "Masquerade Domain" and "Smart
Host".

Apart from that I think I will wait for my ISP to answer the
reverse DNS thingo.

Malcolm

 

Do not check/enable that RDNS setting, it doesn't do what
you think it does and actually is harmful.

That setting will cause Exch to do a lookup and if the
sender can't be verified Exch will <modify the headers to
permit routing>, not deny.



That's actually the opposite of what most people want to
happen...

Tony Su

 

Thanks Tony

That is worth noting. It _is_ a bit ambiguous.

I was actually having second thoughts about it and had
already unticked it.

Malcolm

 

(actually, it has to be done by whomever owns the IP netblock)