Outgoing email is stuck in queue 1

[LadySlinger]

One of my users sent an email to a customer a few days ago. The customer is able to send emails to the user, but for some reason the responses from the user are stuck in the queue for sending.

The event log shows Event ID 4006 with

Message delivery to the host 'xx.xx.xx.xx' failed while delivering to the remote domain 'domain.com' for the following reason: An SMTP protocol error occurred.

That is the only domain that our mail server cannot send to.

I ping the IP address with no results. I ran a tracert and the results only went as far as their ISP and stopped responding for the remaining 9 hops.

 

[LadySlinger]

PS, I just tried to telnet via port 25 and the results I received were:

554 <mailserver.domain.com>

Connection to host lost.

 

[kestrel1]

Have you tried sending to this domain from another user account?

 

[LadySlinger]

I sent an email this morning to the same domain from my email account and its still stuck (2 hours later).

We have had about 100 other emails leave the network without any issues.

 

[kestrel1]

I suspect that your ISP is blocking this domain for some reason. Have you tried contacting them, to see if this is the case?

 

[58sniper]

I suspect that your ISP is blocking this domain for some reason. Have you tried contacting them, to see if this is the case?

That's likely the case. Could be your IP is blacklisted. Go to

http://www.dnsstuff.com/

and check.

It could be your reverse DNS is either missing or incorrect. Run that test as well.

Could be (although more unlikely than the above), that the receiving side is checking SPF records, and yours does not exist or is incorrect.

Pat Richard, MCSE MCSA:Messaging CNA
Microsoft Exchange MVP
Want to know how email works? Read for yourself -

http://www.ietf.org/rfc/rfc2821.txt

 

[LadySlinger]

I emailed our ISP who told us that they have nothing to do with our email, so I need to contact the people in charge of our domain.

I have put in the request and am waiting for someone to contact me.

I did check dnsstuff.com and we are not registers on any spam databases listed there. Neither is the IP address of the company we are trying to reach.

I ran a Reverse DNS lookup and a successful return occurred for both our IP and the customer's IP.

 

[58sniper]

ok. Spam checks and rDNS checks for the receiving side don't matter.

Your ISP would only be involved in maintaining the rDNS record.

The receiving side might be doing some other type of connection filtering.

Pat Richard, MCSE MCSA:Messaging CNA
Microsoft Exchange MVP
Want to know how email works? Read for yourself -

http://www.ietf.org/rfc/rfc2821.txt

 

[LadySlinger]

The latest update is that
1) I still haven't heard back from my ISP.

2) I have another email that happens to be going to the same host (but different domain) in Italy that is stuck in queue.

I went to

http://www.dnsstuff.com

again and ran a tracert. The tracert was able to reach all the way to the destination host and that's when the connection dropped (after 4 tries). DNSstuff said that there probably was a firewall on the other end that does not allow pinging for them to continue on.

Does this make sense?

 

[kestrel1]

Yes a firewall could block a ping attempt, but it shouldn't block an email unless the firewall has been set to reject a domain. I don't know why it would be stuck in your queue though. Normally an email would go from your local network to your email server (ISP or local) & then on to the destination. If it was rejected by the destination server, you would normally recieve an error report back in your inbox. Who host's your email? is it your ISP or do you have an email server on your network?

 

[LadySlinger]

Our ISP just hosts our internet access.

We host our email.

I keep checking the firewall logs, but everything is green. Each time the connection attempt is logged it appears fine. I can't find anything from that server that is being blocked at the same time.

 

[LadySlinger]

The email issues are back.

I have contacted our ISP (again) and they're insisting that its the virtual SMTP server, not their dns servers.

I ran Wireshark and saw that there was a TCP checksum error (Bad Checksum: True). I set the Checksum Offload to none. Still haven't gone through.

There is another client that has been trying to email us, but they receive a Winsock Error 10060.

Anymore thoughts?

 

[kestrel1]

I would say that you have a setting on your virtual SMTP server that isn't right. Get the settings checked to make sure there is nothing wrong there.

 

[123itman]

have you ever gotten this resolved. I am having the exact same error.

Thanks