Can't send external email,  Exchange 2007

Cizombs used Ask the Experts™
I can't send external email using exchange 2007.  I can receive with no issues.  I can send email to anyone on the domain but can't send to any external addresses.  Port 25 was opened by ATT (by request).  I will get an exchange error message stating this message cannot be send and exchange will try again.  Any suggestions.  Running SBS 2008 with exchange 2007.
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What is the full exchange error?
Also on the server open up EMC - go to organization configuration - hub transport - and have a look at your internet send it enabled and does it  have the right settings?
Rajith EnchiparambilOffice 365 & Exchange Architect

Exchange 2007 doesn't come with a send connector by default and hence you can't send emails outside by default.

Configure a send connector with address space as * if you don't have it yet.
From your exchange server try running a port 25 test to make sure the port is available. Open command prompt and try to telnet to yahoo's mail server to test smtp.
telnet 25
you should get something that says SMTP Ready. If not please post response.

Next I would try to check spam db. Go to and select "Internet Email Test" -> "Outbound SMTP Email. Type in the external IP address of your mail server and your email address. Let it run tests.

If all the above test run fine, then we can take a look at your exchange config.


Thanks for the great info.  Send connector was configured.  When I disabled the smarthost everything seems to work fine so maybe there's a clue???  I re-enabled the smarthost and the issue sending was back.  I know the smarthost uses port 465 where SBS uses 25, so maybe another clue.  

How do I determine the external IP address of my mail server?  

When I disabled the smarthost everything seems to work fine => meaning if you use DNS to route email it works fine ? Port 465 is secure smtp, so your smarthost uses secure smtp  ?

This smarthost is you service provider or some other box ? Since you are able to send emails via DNS directly I guess your exchange server is connected directly to the internet,correct ?

Finally do you have a service provider which routes your email or not ? If yes, please check with them on smarthost settings and secure smtp settings (authentication etc)

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