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421 4.4.2 connection dropped issue with exchange 2007

Posted on 2011-10-11
Medium Priority
Last Modified: 2012-05-12
Hello all

I seem to be having some bother with an exchange 2007 server - some mails seem to get queued with the error:

421 4.4.2 connection dropped.

There is a valid PTR record set up (I have confrimed this) and there doesn't appear to be anything unual going on with the exchange set up.

The domain has 4 mx records set up to direct to googles postini service and this shouldn't effect anything - this is also for incoming only. There is no other software on the server that direct relates to exchange (ie. norton etc.).

Most mails seem to send fine and a few that are queued are eventually delivered. There are a couple of domains though that they cannot send mail to at all, Delay notification and the NDR - 421 4.4.2.

When I try to telnet a mail to one of the domains it goes through fine, one of the others reports error 451 mail server temporary failed.

Any ideas what is up?

Many thanks!
Question by:badpilot
  • 5
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LVL 19

Expert Comment

by:Raheman M. Abdul
ID: 36949871

1. If you are attaching the files, rename the extention to .file or .txt etc then try again.
2. could be your PIX firewall strange behaviour if you have.
3. Verify your DNS records. Refer for details: http://exchange.sembee.info/network/dnsconfig.asp 
4. Are you using Cisco ASA? If yes, then try disabling Inspect ESMTP

LVL 19

Expert Comment

by:Raheman M. Abdul
ID: 36949893
To disable/uncheck ESMTP, under Rule Action, Protocol Inspection, uncheck ESMTP

Author Comment

ID: 36955857
Hi marahman,

thanks for this.

1. No attatchments.
2. No PIX firewall
3. DNS records all appear to be in order
4. No Cisco ASA

I don't feel ESMTP will be causing the problem as 99% of servers support this now and even if not if a correct response isn't received after sending EHLO exchange will try and resend with HELO instead. I've disabled this though and will test and get back to you.

For anyone looking to disable ESMTP on exchange 2007 use the management shell and issue command:

Set-SendConnector -Identity "<name of your send connector>" -ForceHELO $true

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Author Comment

ID: 36956007
Nope, still getting 541 mail server temporary failed from one and 421 from another.



Author Comment

ID: 36956008
Sorry that was meant to be 451 instead of 541

Accepted Solution

badpilot earned 0 total points
ID: 36993015
Turns out it was an issue with our ISPs DNS - using OpenDNS resolved the issue.

Author Closing Comment

ID: 37016562
Provided solution myself.

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