*** DNS and SMTP Service Problem *** 1

[jonnywah]

I use SMTP Service in Win2K to send email. I have SMTP "Virtual" Server set up in IIS, but this
is not the same as Exchange Server. No DNS server is
used.

About 20% of my emails are stuck in queue. I get the following messages in Event Viewer:

Message delivery to the remote domain 'somedomain.com' failed for the following reason: The remote server did not respond to a connection attempt.

Message delivery to the remote domain 'somedomain.com' failed for the following reason: An SMTP protocol error occured.

Message delivery to the remote domain 'somedomain.com' failed for the following reason: Unable to bind to the destination server in DNS.

Message delivery to the remote domain 'somedomain.com' failed for the following reason: Unable to successfully to the remote server.

Message delivery to the remote domain 'somedomain.com' failed. The error message is 'An SMTP protocol error occurred'. The SMTP verb which caused the error is 'HELO'. The response from the remote server is '501 Syntactically invalid HELO argument(s).

I checked with dnsstuff.com, and it says "No CNAME records exists for mydomain.com", and "No PTR record exists for mydomain.com". What is the problem? How can I fix this? Why are 80% of the emails going through, and the other 20% don't get sent?

Please help. Any suggestions or information would be appreciated. Thank you in advance.

 

[Serbtastic]

It sounds like a problem with somedomain.com's mail server.

 

[jonnywah]

Any other suggestions or information? MX records?

 

[ChrisAC]

If you don't have a correct PTR record for your domain then that would cause some connections to fail when connecting to mail servers that do reverse DNS checking.

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************

 

[jonnywah]

How do you set up PTR record? Would this be done by the DNS server that is for the incoming traffic (2 DNS servers), or by the DNS server that is sending mail out? (2 different DNS servers).

 

[ChrisAC]

The PTR record is configured on the server that is authoratative for the reverse zone. So, if your mail server was on IP address 1.2.3.4 then the reverse zone would be on the server that has the 3.2.1.in-addr.arpa zone delegated to it.

If you got your IP addresses from your ISP then speak to them about reverse DNS as they will most likely have the reverse zone for their addresses delegated to their DNS servers.

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************

 

[jonnywah]

Chris,

You've been a great help! Thank you.