The maildir standard mailbox format is described in maildir(5).

• Each maildir contains a set of subdirectories: cur, new and tmp.
• Enhanced maildirs support subfoldering through contained maildirs whose name starts with a dot (e.g. maildir/.sub/{cur,new,tmp}).
• Many IMAP implementations are maildir compatible.

• Each subfolder name by convention has a leading dot (.).
• The internal structure of a subfolder is exactly the same as a regular maildir, i.e. the three subdirectories cur, new and tmp must exist.

Subfolders of a subfolder don't reside in the subfolder! I.e. the hierarchy ends on the subfolder level, all consecutive subfolders are constructed by using special names. See the following example:

$HOME/Maildir/cur
$HOME/Maildir/new
$HOME/Maildir/tmp

$HOME/Maildir/.Folder
$HOME/Maildir/.Folder/cur
$HOME/Maildir/.Folder/new
$HOME/Maildir/.Folder/tmp

$HOME/Maildir/.Folder.Sub
$HOME/Maildir/.Folder.Sub/cur
$HOME/Maildir/.Folder.Sub/new
$HOME/Maildir/.Folder.Sub/tmp

Here Sub is a subfolder of the subfolder Folder.

Is a simple script to create maildirs or maildir subfolders.

Use the following command to create a subfolder inside a maildir:

maildirmake -f <SubfolderName> <PathToMaildir>