Hi Chris,

 

This help document should be able to shed some light onto this for you: SmarterMail in High-Volume Deployments. I don't know the specs, but I do know that SmarterMail is capable of having more than 40,000 users on one server - and that's with the users relying on webmail, IMAP, lots of contacts, etc. When you remove those things and limit the server even more (users have no access to the Web interface, POP their messages to email clients, are not allowed to store anything on the server, etc.), I've heard of one instance with more than 100,000 users. 

 

If you don't get the technical feedback you want here, go ahead and call into our sales department. You can talk with one of our technical sales specialists and they can give you some more information. The number is 877-357-6278. 

 

Hope this helps!