Importing 1500 email users.

I need to import about 1500 email users. I setup the domains already and the few forwarding accounts we have but would prefer not to do all 1500 email accounts. What is the best way to get them in the system. Moving their emails over is no problem once their accounts are setup properly in the system. I have all the clear text passwords for all the email accounts as well.

 

I see I need to use remoting. Looking for the documentation for it now.