the mail account name must be login name ?
 

I configure a mail server with sendmail and qpopper.
must the mail account name be the user login name?
I mean, Is there any method that i needn't to adduser as linux user, only let him own a mail account?

question 2: how can i change mail users display name.
fg: one user name is joe. and his mail account is joe@company.com, when he send mail to me , in my mail agent, the sender is joe. what should i do if i want the display name is "joe williams"?

thanks