If I use LDAP as varification method.Where are mails store?

[liu zhi]

Now I learn that I can use LDAP as POP3 varification.
But I wonder that what should I do to store so much users mails?
Is it necessary to add folders to /home directory.and Is each user need a .qmail file?
And more complex environment.I have many virtual domain.How can I do to store users' 
mails.
Thanks a lot to read the message.