Suppose that I have a normal user account dropbox@mydomain.com with its own mailbox, I want to create two individual users abc@mydomain.com and xyz@mydomain.com but they don't need to have separate mailboxes I want them to act like email aliases but with a different password for every alias, so that when I use them in any of my programs I'm not leaking out my main admin password. I can create separate users but I don't need all those mailboxes.

Is there any way to do this ?