Below is some information about how the changeover to maildir format for our mail server will affect the usual mail reading clients that people use: pine, thunderbird, and webmail. At the very end is more detail about the changeover.

If at first you cannot find your mail messages in pine don't panic,

        1) try:    "<" then ">"       to see subfolders 
        2) try:    "<" then "V"       to see messages 
        3) do NOT use the Enter key until you get used to the new
           defaults that pine uses or you may become confused.

When you try to view a folder your messages are almost surely still around, but you may be viewing a (possibly empty) directory of subfolders as opposed to the folder of messages or you may be viewing a (possibly empty) folder of messages when you really want to see the subfolders directory. The explanation follows.

All folders (except INBOX) can normally contain both messages and subfolders and such folders are displayed with [.] at the end for their names in pine's FOLDER LISTs (you will notice that INBOX does not have [.] after it since it cannot have subfolders). Previously pine only had View Fldr (>), which was the default action when typing the Enter key. This would show the messages in a folder.

There are now two related concepts View Fldr (V) and View Dir (>) (yes, the default character for View Fldr has changed when viewing a folder that can have subfolders; that may not seem like a good thing but that is how pine does it). View Fldr still means to see the messages in a folder, but View Dir means to see the list of subfolders in that folder.

The default action when typing the Enter key is still View Fldr but if you have a folder with periods in its name, say my.class, when you are in the my folder you really want to see the list of subfolders to find the class folder and then you want to open the messages in that folder, so typing the Enter key in the my folder will not do what you want.

The departmental mail server is changing its message storage format to maildir. The four main differences are that mail messages will now be more efficiently served to your mail reader (it may be a little slower the first time but from then on it should be faster) and stored for backups, folders can now store both messages and subfolders, maildir does not allow periods to be used in folder names, and only email whitelists and blacklists are directly supported for email filtering since PureMessage is doing spam filtering now.

maildir is a slightly different way of storing mail messages on mail servers than the old one large file with many messages method. The older method was fine when people had small mail files, but now people tend to have larger folders. maildir uses one file per message. The old method made the processing and backing up of email much less efficient. We will be somewhat increasing the email quota because of this.

maildir also allows mail folders to contain both messages and subfolders. In the previous system folders could only contain one or the other. This means that one can have a classes folder with general messages about classes in it and also folders inside there for individual classes. This may take some getting used to.

Actually maildir does allow periods in folder names but due to its internal storage method this can result in folders that cannot contain messages. Some clients will still try to create such folders and in that case you may not actually be able to save messages in the folder or in some component of it. Unless you are truly adventurous it would probably be best to avoid trying to use periods in your folder names.