An Exchange2007 Transport Protocol Agent which provides the (MTA) catchall functionality.
Exchange2007 (like Exchange 2003) doesn't provide CatchAll functionality. CatchAll is the ability of an SMTP server to redirect messages to non-existing recipients to a specific address.
This CatchAllAgent is an Exchange 2007 Transport Agent. The CatchAllAgent can be configured to redirect the recipient address for unknown recipients to a 'catchall' address such that such messages end up in a dedicated mailbox. The configuration allows for multiple domains, but you can only specify a single target address for each of those domains.