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We recently installed an Exchange 2010 Server and we are having some problems sending emails to certain domains. Email is stuck in the queue with 421 4.2.2 Connection dropped due to SocketError.

Any Suggestion? The below is the message when using telnet command:

EHLO ******* Hello [********]
250-SIZE 15360000
250 OK
MAIL FROM:*******
250 2.1.0 *********....Sender OK
RCPT NOTIFY=success,failure
**550 5.7.1 Your email messages have been blocked by the recipient OR by Trend Mic
ro Email Reputation Service. Contact the recipient or his/her administrator usin
g alternate means to resolve the issue.**
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what happens when you send using telnet from the exchange server? can you post a transcript? – dyasny Jan 18 '11 at 8:49
hi refer to my amended message! Thanks – e0594cn Jan 19 '11 at 8:50

Did you even read the error message?

Your mail is being blocked by because they deemed you ( not trustworthy.

It's quite clear what you have to do (it's even noted in the 550 response!):

You have to contact them to know about what the particular issue is. It's either a misconfiguration on their part, or on your part. It seems that they are at fault, since a quick search did not yield any particular issues with your mailserver.

Do note however that your second MX seems to be down.

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I've had a similar problem, albeit not with trend micro.

Check your reverse DNS on the public IP for your mail server matches your FQDN in the exchange connector.

Problem I had with a client was sending emails to AOL - They refused emails because of the this. Worth a look at least.

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Hm, the remote host was quite definitive in sending a 5.x.y and telling you that he's not interested in your message. Seems a quirk of your server that despite a fatal error it thinks he should try again later...

I don't see directly how the initial 421 relates to the 550 --- what happened next in the transcript, did the remote server maybe drop the connection instead of waiting for you to quit?

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Hi, the remote server drop the connection! How can i resolve this issue? Thanks! – e0594cn Jan 19 '11 at 10:26
You can check your e-mail reputation with Trend Micro here: You may also want to check to make sure that you are not operating an open relay, and use one of the online services to make sure you are not on any RBL's. – Sarah C. Corriher Aug 5 '12 at 5:49

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