Solved

Exchange 2010 - 451 4.4.0 DNS query failed

Posted on 2014-02-27
8
2,728 Views
Last Modified: 2014-03-22
Hi Guys,

We just started using mimecast for spam filtering, inbound emails works fine but problem is with the outbound emails.

Basically email should be routed through the mimecast servers but when use the mimecast's server FQDN on the send connector the email gets stuck in the queue with the 451 4.4.0 DNS query failed error ( see attached ).

I thought it was DNS issue with the exchange server and for that reason I ran a nslookup but it resolved the names properly, then I tried with telnet and I was able to connect and even to sent emails through the eu-smtp-outbound-1.mimecast.com server.

This is not a firewall issue because I am able to run telnet tests.

I have been working on this for the past 2 days but still unable to figure it out :(
Queue.jpg
0
Comment
Question by:R2_D2
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
8 Comments
 
LVL 26

Expert Comment

by:DrDave242
ID: 39892410
Did you follow the procedure shown here for setting up the SMTP connector?
0
 
LVL 63

Expert Comment

by:Simon Butler (Sembee)
ID: 39892425
Check whether you have external DNS servers listed on the Receive Connector. That can sometimes cause this problem.

Also be aware of this issue with DNS:
http://support.microsoft.com/kb/2508835

That can be caused by some firewalls.

Simon.
0
 

Author Comment

by:R2_D2
ID: 39894382
DrDave242, I did follow the instrucitons from the link but didnt help.

Simon, my exchange server is win2012 and the patch was incompatible.
Also my default received connector had some IP addresses on the " receive mail from remote servers that have these ip addresses " and i just removed them and left the default settings " 0.0.0.0-255.255.255.255" and "::ffff.ffff.ffff.ffff "but unfortunately it did't fix it :(

this issue is very weird.
0
Free learning courses: Active Directory Deep Dive

Get a firm grasp on your IT environment when you learn Active Directory best practices with Veeam! Watch all, or choose any amount, of this three-part webinar series to improve your skills. From the basics to virtualization and backup, we got you covered.

 
LVL 27

Accepted Solution

by:
skullnobrains earned 500 total points
ID: 39896272
in the properties of the smarthostdeliveryconnector, Network tab,

try to check "Use the External DNS Lookup settings ont the transport server"

if already checked, try to specify dns servers explicitely

---

as a quick workaround for the time being, adding a line in the hosts table or using the ip addresses associated with the mimecast server in the connector should work
0
 

Author Comment

by:R2_D2
ID: 39897576
tried with the "Use the External DNS Lookup settings ont the transport server" but didn't work neither.

How can i  specify dns servers explicitely ??

Finaly, I didn't edit the host file because the eu-smtp-outbound-1.mimecast.com resolves to a large range of ip addresses.
0
 
LVL 27

Expert Comment

by:skullnobrains
ID: 39898294
through the properties of the "external dns servers"

you can associate as many ip addresses you want with a single name in a host file by adding multiple lines. this is only a poor man's workaround

can you confirm that running nslookup on the exchange server gives the proper address ?
0
 

Author Comment

by:R2_D2
ID: 39931175
Sorry for the late reply.

The Setting "Use the External DNS Lookup settings on the transport server" and restarting the exchange server fixed the problem.

Thank you for your help.
0
 
LVL 27

Expert Comment

by:skullnobrains
ID: 39947122
good to know this required a restart. thanks for sharing

best regards
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Find out what you should include to make the best professional email signature for your organization.
This article aims to explain the working of CircularLogArchiver. This tool was designed to solve the buildup of log file in cases where systems do not support circular logging or where circular logging is not enabled
In this video we show how to create an Address List in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Organization >> Ad…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an antispam), the admini…

752 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question