Read the list of mailboxes.
An IMAP stream returned by imap_open().
ref should normally be just the server
specification as described in imap_open().
Specifies where in the mailbox hierarchy to start searching.
There are two special characters you can pass as part of the
pattern: '*' and '%'. '*' means to return
all mailboxes. If you pass
pattern as '*',
you will get a list of the entire mailbox hierarchy. '%' means to
return the current level only. '%' as the
pattern parameter will return only the top
level mailboxes; '~/mail/%' on UW_IMAPD will return every mailbox
in the ~/mail directory, but none in subfolders of that
Example 1. imap_list() example