Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (Full Version)

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bhavin78 -> Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (24.Jun.2008 7:39:47 PM)

I just published Exchage server 2003 on ISA Server 2006, I am not able to send email  to servers requiring reverse DNS lookup  (aol,dyndns, juno etc). Email to this server are not deliver and in the Email header it has primary address of ISA Server Ext NIC , Why? What I need to configure so it has IP of ISA Server EXT NIC (used for Exchange server)
We have created MX record on our DNS server which points to Internal NIC of exchange server.

How and where do I change the PTR record to point to IP address used for Exchange Publishing ?


Can I get some help please?



paulo.oliveira -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 7:30:22 AM)

Hi,

when your mail server sends an e-mail, it first send it to ISA and ISA do the NAT of the private addres to a public IP configured on ISAīs external NIC. Is the same when you access a webpage.

quote:

We have created MX record on our DNS server which points to Internal NIC of exchange server.

Wich DNS server the internal ou external? Why your MX record is pointing to an internal IP?

Regards,
Paulo Oliveira.



IanC -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 7:33:25 AM)

Outbound mail will always use the primary IP address of ISA's external NIC as its source.  You will need to add a PTR record to your external DNS zone pointing to this address.

Ian 



bhavin78 -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 11:50:12 AM)

I do not have external dnz zone on my internal dns server, I created one and addedd host record mail1.domain.com which points to EXT NIC of ISA (for exchange not the primary address)
it is still not working.

do I need to call my ISP to look into my PTR record?



paulo.oliveira -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 1:02:42 PM)

Hi,

to clear it up, if donīt configure a PTR record in your DNS server doesnīt mean that your mail server wonīt work. The problem occurs only when you try to send an e-mail to a mail server that makes reverse DNS check.
But, for follow the best practice, you should ask your ISP to create a PTR record for ISA primary IP address and your external mail server IP address.

Regards,
Paulo Oliveira.



bhavin78 -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 4:50:47 PM)

Paulo,
Called ISP and found out the PTR record for mx was there but was missing for domain name. Adding PTR record for domain took care of the problem.
Why PTR record is not created automatically on ISP's server ?

Thanks everyone for your help



paulo.oliveira -> RE: Email Header is ISA's EXT NIC Address, Cannot Send email to servers requiring reverse DNS lookup (25.Jun.2008 5:03:46 PM)

Hi,

glad you could make it!
This is a manual job and not all DNS records needs a PTR record. [:D]

Regards,
Paulo Oliveira.



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