Hello all. I have a question about Exchange 2003 Enterprise Edition. I was hoping someone could explain to me the issue of CALs when it comes to Exchange. We currently use 2003 Standard Edition and would like to upgrade to the Enterprise Edition. We would like to make use of multiple Databases as well as the increased Information Store capacity. Do the CALs follow the number of mailboxes? Are there any issues I should be aware of going from one to the other? I am still getting the hang of Exchange in general after having it dropped in my lap a while back. Unfortunately you only learn things when you are troubleshooting a problem or installing something new and have to worry about compatibility issues.