Courier-IMAP Global Shared IMAP Folders

Contents 1 Overview 2 Configuration 3 Courier-IMAP Configuration 4 Accessing Shared IMAP Folders 5 Client Testing via IMAP 6 NOTES

Overview

(From maildirmake(1))

"This is another extension to the Maildir format that allows folders to be shared between multiple clients."

This allows users to use the IMAP server as a pseudo list server for quickly reaching everyone without going thru an elaborate newsgroup or mailing list. Currently, I am using shared folders to publish notices to all users.

Configuration

1. The global shared folder holder is in /home/shared-maildirs/
2. /home/shared-maildirs/Notices is the root Maildir which contains many more shared folders.
3. /home/shared-maildirs/Notices/.Domain.com contains is the actual shared folder mean for posting messages. This will be world writeable.

[root@mail Notices]# mkdir -p /home/shared-maildirs/
[root@mail Notices]# maildirmake -S /home/shared-maildirs/Notices
[root@mail Notices]# maildirmake -s write -f Domain.com /home/shared-maildirs/Notices

[root@mail root]# ls -ld /home/shared-maildirs/
drwxr-xr-x    3 root     root         4096 Oct 13 12:47 /home/shared-maildirs/
[root@mail root]# ls -ld /home/shared-maildirs/Notices/
drwxr-xr-x    6 root     root         4096 Oct 13 12:47 /home/shared-maildirs/Notices/
[root@mail root]# ls -ld /home/shared-maildirs/Notices/.Domain.com/
drwxr-xr-t    5 root     root         4096 Oct 13 12:23 /home/shared-maildirs/Notices/.Domain.com

Courier-IMAP Configuration

[root@mail Notices]# echo "Notices /home/shared-maildirs/Notices" > /usr/lib/courier-imap/etc/maildirshared 
[root@mail Notices]# cat /usr/lib/courier-imap/etc/maildirshared 
Notices /home/shared-maildirs/Notices

• Restart the Imap service.

Accessing Shared IMAP Folders

You will have to "subscribe" to this folder if it does not automatically appear in your mail client. Use your mailer's "Post Message To Folder" feature to post messages to the shared folder. Since the posting procedure varies from mailer to mailer, please refer to the user documentation for specifics.

Client Testing via IMAP

See http://www.inter7.com/courierimap/README.imap.html for client compatibility notes.

• Evolution 1.4.5: SUCCESS

The shared folder was listed automatically when I created a new IMAP account. In the case of an existing account, the new shared folder had to subscibed manually. Posted a message to the shared folder using "New->Post Message" (CTRL+SHIFT+P) function successfully.

http://www.ximian.com/products/ximian_evolution/

• HushMail 0.6: SUCCESS

The folder dropdown list listed the newly added shared folders on login. HushMail is considered to be a really fast, secure and simplistic webmailer but I personally found it *too* simple. My users are def not gonna use HushMail.

• Sqwebmail 3.6.0: SUCCESS

Sqweb would be the apt choice with Courier-IMAP, unfortunately, it requires direct accesss to the Maildirs which is not possible in my case. The webmailer and the mail store are on differrent hosts.

SqwebMail is a web CGI client for Maildir and not IMAP.

• Squirrelmail 1.2.11: FAILURE

The default webmail shipped with RedHat 8 did not automatically list the shared folders when I logged in. I am not too sure whether it supports the shared folder extension. Need to find a more featureful webmailer which supports more IMAP extensions.

• Outlook: TODO

• Mozilla: TODO

NOTES

• Shared folders are stored under /home to simplify backups. The maildirmake(1) man page suggests using /usr/local/share/maildirs/ which I think is more appropriate for this purpose.

• I dont know how to create user shared maildirs via the IMAP client. AFAIK, the user has to have shell access to the "maildirmake" commands before he can export it.

• SqWebMail (The preferred webmailer with Courier-IMAP) I think supports the shared folder extension but I cant use it on my site since the IMAP server and the webmail server are on different hosts. SqWebMail does direct Maildir access.