SMTP communication problem with recipient's email server. Suspect recipient is requiring reverse lookup

I am getting the following info in the undeliverable response when trying to send email to a particular domain,

 rcpt@rcptdomain.com on 06/06/2006 9:15 AM
            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

            <myemailserver.my-domain.local #5.5.0 smtp;573 Validating Sender>

1. I suspect that the recipient server is doing a reverse lookup to validate our domain. Our ISP own's the static IP issued to us therefore I expect that they would have to make the reverse lookup entry in thier DNS. Is this correct?

2. I thought the the 573 error was a generic response meaning the server is not available. How does the text "Validating Sender" get in the response message?

3. I tried telnet rcptdomain.com 25
ehlo my-domain.com
and got
250 anothermailserver.com your name is not my-domain.com

Our name is my-domain.com but would not be available by reverse lookup as discussed above.

Are my assumptions correct? What is the fix?


DaveChoiceTechAsked:
Who is Participating?
 
SembeeConnect With a Mentor Commented:
If you don't have a reverse lookup, and you cannot get one, then you should probably setup an SMTP Connector to route email for this domain through your ISPs SMTP Server. You will find an increasing number of sites will not accept email from servers without a reverse lookup.

Simon.
0
 
rakeshmiglaniCommented:
try running the test mentioned in

http://www.checkdns.net/quickcheck.aspx
http://www.dnsstuff.com/

and check whether any errors are reported for your domain
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DaveChoiceTechAuthor Commented:
No problems reported by http://www.checkdns.net/quickcheck.aspx

http://www.dnsstuff.com/ on our IP shows there is no PTR record as expected and that email is being accepted by the the recipient we are trying to send to.

My understanding is that , I don't have control over the PTR records for a static IP provided to me by my ISP so I have requested they make this update to resolve the reverse lookup. Is this the right thing to do?

Thanks for the links. Very useful.
0
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ExchgenCommented:
You need to call the remote server admin and have them add your domain in their whitelist.

This is a process used by comcast, where in they accept emails only from domains who requested to send email to them.

Raghu
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DaveChoiceTechAuthor Commented:
Raghu,

I don't think the whilelist is the issue. I used www.dnsstuff.com to test if the recipients email address was accepting email and it was. If whitelisting was the problem then I suspect that dnsstuff.com would not have being able to make this test successfully.

Dave
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ExchgenCommented:
I say this is an issue with the remote domain, because the moment you say EHLO, the remote domain is doing a reverse query where in it checks the sender domain and the sender IP.

If you have an "A" record pointing to your domain, and a valid PRT in place for the outgoing IP, then issue is indeed blacklisting.

The filtering is happening at the connectuion level and is giving you the answer as "your name is not my-domain.com".

Consider getting the above changes and then test to confirm if blacklisting is the issue or the missing records is the issue.

Raghu
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DaveChoiceTechAuthor Commented:
Raghu,

As I described above I do not believe we have a valid PTR record. It is not under our control. The A record and MX record test out ok.

Dave
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ExchgenCommented:
Dave,

Better speak to the remote domain administrator to get an in-sight.

Raghu
0
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