Solved

Exchange error sending to certain domains "421 4.2.1 unable to connect"

Posted on 2014-10-28
2
465 Views
Last Modified: 2015-01-23
I am not an exchange guru but I know enough to be dangerous.
I havs an SBS2011 with Exchange 2010 for my business (5 users). Mail is working for the most part however there are a few domains that we can not send mail to. The messages sit in the queue until they finaly fail. The error we are getting is:

451 4.4.0 Primary Target IP address responded with: "421 4.2.1 unable to connect." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.

95% of our messages get delivered just fine, with the exception of a few domains where we get the above error. We are not on any SPAM blacklists. I don't know where to begin.

Please help.
0
Comment
Question by:wilkox1
[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
2 Comments
 
LVL 16

Expert Comment

by:Postmaster
ID: 40409988
Try an MX record lookup (http://mxtoolbox.com/SuperTool.aspx#) of the destination SMTP domain.
This will show you the public IP for that mail server - make sure your system is talking to the same IP that is shown.

It may be that you have an entry in your own DNS for that domain - if so remove it to force the lookup to go external and get the right IP.

If the IP looks OK - then you may need to contact the IT support of the company and seek an advice.
0
 
LVL 12

Accepted Solution

by:
Md. Mojahid earned 500 total points
ID: 40409993
0

Featured Post

Has Powershell sent you back into the Stone Age?

If managing Active Directory using Windows Powershell® is making you feel like you stepped back in time, you are not alone.  For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why.

Question has a verified solution.

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

Learn to move / copy / export exchange contacts to iPhone without using any software. Also see the issues in configuration of exchange with iPhone to migrate contacts.
Unified and professional email signatures help maintain a consistent company brand image to the outside world. This article shows how to create an email signature in Exchange Server 2010 using a transport rule and how to overcome native limitations …
To show how to generate a certificate request 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 Servers >> Certificates…
how to add IIS SMTP to handle application/Scanner relays into office 365.

734 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