The MailCOPA email client allows any number of users to login to it. Users may choose to have a password to protect their user-account. Each user-account may have multiple email accounts, multiple address books as well as sharing email accounts with other users.
If you purchase a multi-machine license of the MailCOPA email software then different users can log into their accounts on different machines. The data is accessed from the server machine allowing sharing amongst the multiple machines. Folders can be shared between users and accessed in real time on different machines, or a very powerful feature allows you to log in as the same user on several machines and see all your email and updates occur in real time on several machines at once. This is a great feature for customers running support desks where several users may need to see the same email at the same time.