Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

Professional Opinions
Ask a Question
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE

troubleshooting Question

"421 4.4.2 Connection Dropped"

Avatar of mikegaston3127
mikegaston3127 asked on
12 Comments1 Solution2388 ViewsLast Modified:
I just migrated a client from Exchange 2003 to Exchange 2007. No issues with the migration. Uninstalled Exchange 2003. No issues. The only problem I am seeing now is a problem with three domains users are trying to send mail to. Mail to other domains works without issue. In all problem cases delivery fails with "421 4.4.2 Connection Dropped" errors. Outbound smtp logs show

2009-02-26T19:21:52.304Z,Outbound,08CB665E9CA0DE03,0,,,*,,attempting to connect

It's my understanding that the remote servers are dropping the connection. When I attempt to telnet to the servers in question on port 25 from the clients server, I connect but no helo or ehlo banner is displayed. I simply get a blinking cursor and then the connection times out. When I telnet to the same servers from my own server I get the proper response.

I have checked DNS for both my clients server and the recipients server. All of it checks out both forward and reverse lookups. Outgoing mail from my clients server displays the correct FQDN name. My client servers IP is not on any blacklists.

I'm stumped!

Avatar of mikegaston3127

Our community of experts have been thoroughly vetted for their expertise and industry experience.

This problem has been solved!
Unlock 1 Answer and 12 Comments.
See Answers