In Exchange 2003 we could prevend sending to a domain with delivery rectrictions. In Exchange 2007 we can do this by using transport rules _this can be created on the Hub Transport server. When we start the wizard and specify the name the next step is to define the _conditions, here we choose the following options:
- from users inside the organization
- when a message header contains specific words, here we specify that we want to check the parameter to which has the value blockeddomain.com __
The next step is choosing the correct action, we could for example bounce the e-mail back to the sender which contains a message that sending to this domain is prohibited by security settings.
- send bounce message to sender with enhanced status code
The last step we could use is the exceptions, this can be used to allow a specific address that is part of a domain that we will block.