I have a single Exchange Server 2003 setup and it is sending and receiving emails to users very well to and from our network to the outside world.I also have Antigen 9.1 installed and I am getting the postmaster messages to my Administrator email account, but I am not getting any of the regular traffic inbound or outbound from our network users into that account. Is there a way I can capture those messages so that I can forward them along back to management or the users if needed ?

The one quick way to capture all messages going into or out of a databse is to turn on message journaling on the database(s) the mailboxes are on, and have them all dump into a collection mailbox. This mailbox generally fills up real quick, and you place an additional load on the Exchange 2003 server as you are asking it to do 2x the amount of work for every email message. You could write an SMTP event sync if you only wanted messages going into or out of your Org, but that requires some skill in 2003. You could look to various examples of how to add a disclaimer footer to outbound messages with a 2003 event sync if you wanted to know what that process looks like. I am not aware of how to do it with Antigen, and that really isn't what the product was designed for anyway. The best recommendation I can give you is to upgrade to Exchange 2007, and then use a transport rule (much like an Outlook rule) to forward messages going into or out of your Org to a collection mailbox. The benefit here is you can have the Hub Transport role on another server, and thus offload the processing of the rule processing to a seperate system.