PHP COURIER NOTES

This file describes php courier concepts at a very high level.

For any detail, refer to the code.

phpCourier manages domains, accounts, mailboxes, and aliases.

Ultimately, all relevant information is stored in the Mail table,
which Courier can read. In addition to updating the Mail table, the
system will create domain directories and will create mailbox
directories within the domain directories.

The general idea is that domains contain accounts, accounts define
mailboxes, and mailboxes have some number of aliases.

There are three types of accounts:

1) Master administrator. The root user. This is the only user type
   that can create/edit/delete domains. The master administrator also
   is the only type that can create administrator accounts. It can
   also create user accounts and edit mailboxes.
   
2) Administrators are assigned to one or more domains and can create
   user accounts and edit mailboxes within those domains.

3) User accounts can be associated with one or more mailboxes,
   depending on the mailbox limit set up for a domain.
   
The system is designed to work in both big domain and little domain
paradigms. In the little domain paradigm, you can create a domain with
a mailbox limit of one per account. The mailbox and account can both
be given the same name and password. Thus every account sees one and
only one mailbox, and the name and password to login are the same used
to fetch mail from the system.

In big domain mode, account names can be different from mailbox
names. Each user can create and administor as many mailboxes as
defined by the domain limits. (Administrators ignore the limits and
can make as many mailboxes and aliases as they want.)

Account names must be unique system wide, but mailbox names must only
be unique within a domain. This causes problems when the system is
used in the little domain paradigm. It is not possible to have account
charlie with mailbox charlie@www.charlie.com and also have another
account charlie with mailbox charlie@www.other.com.

Because of this limit, the big domain paradigm is preferable.  Each
user of the system gets a unique name, but the mailbox will have a
different name.

The administrators have access to the account list for a domain.  The
account list page is modal. That is, it works with only one domain at
a time. The "create a new account" link always creates an account
within the currently selected domain. For administrators that are
associated with only one domain, this is not a problem. However, for
the root account, or for multiple domain administrators, be careful to
always update the display before creating a new account.

The root account can view either administrators or users, and defaults
to viewing administrators.

When a new account is created you are automatically taken to a create
mailbox form to make the first mailbox for the account. The form
offers the account name and password of the mailbox to be the same as
the name and password just entered for the account. You can change the
mailbox name and password, or you can leave the screen without
submitting any mailbox.

Mail directories are always stored as follows. Within the domain's
home directory, a directory that matches the mailbox name will be
created.  Within this directory the Maildir directory will be created
for Courier to use. A domain's home directory can be anywhere that the
web server can see.