I wanted to know is there any way to block an email from being sent a specific email or domain? Ex. I want to block clients from sending email to josh@widgets.com or block any email sent to the domain @widgets.com Is this possible through exchange?

What version of Exchange? In Exchange 2007, you could create a mail-enabled contact for the user and then create a transport rule that redirects messages to this address, or silently drops them, etc. In Exchange 2003, transport rules are not available so one option is to create a new SMTP Connector that has an address space of widgets.com and ensure that this connector has a invalid IP address for the smart host. It has been a while since I've done that but I'm reasonably sure that this method works and that Exchange doesn't try to re-route the message over the generic Internet SMTP Connector. The other option, of course, is to install another 3rd party SMTP server between Exchange and the Internet that allows forfull content control.

You could create an SMTP Connector. In that connector, set if for @widgets.com. Give this connector the highest priority (the lowest number). Now, for the Bridgehead Server that the connector calls for...give it an erroneous IP Address. Anything that is then delivered to any address at widgets.com...will take the route of that connector. But with the erroneous Bridgehead Server identified...it will not get delivered.

Thanks for your reply..... Will we receive a failure notification when mail is sent to this address

I am not certain of that. I am going to say yes...but not certain as it's been a while since I've done it.

If you're referring to the Exchange 2003 option then yes you will receive a failure, once the SMTP service decides it can't route the message (about 48 hours by default as there are several retry intervals in between). If you use Exchange 2007, you can silently drop the messages with transport rules.

Hi...I am running with Exchange 2007 and want to block internal users from sending mails to *@abc.comCan any one guide me for doing the same...I have tried creating mail contact for *@abc.com and creating HT rules for dropping the messages sent to *@abc.com but was not successful.Abhishek