Courier

Courier IMAP is a fast, scalable, enterprise IMAP server that uses Maildirs.

References

• Courier IMAP homepage
  • maildir - E-mail directory
  • Courier FAQ
• On openSUSE:
  • Package doc at /usr/share/doc/packages/courier-authlib and /usr/share/doc/packages/courier-imap.
• On Ubuntu:
  • https://help.ubuntu.com/community/Courier
• Manpages & package documentation:
  • maildirmake(1)
  • couriertcpd(1)
  • imapd(8)
  • userdb(8)
  • makeuserdb(8)
  • /usr/share/doc/courier-doc (on Ubuntu, with package courier-doc installed)

Install

Ubuntu

To install Courier IMAP:

• Install the required packages:

sudo apt-get install courier-imap courier-doc courier-imap-ssl

• Create /etc/courier/userdb.dat

sudo su
pw2userdb >/etc/courier/userdb
chmod 600 /etc/courier/userdb
makeuserdb

• Make sure all users have directory ~/Maildir:

maildirmake /etc/skel/Maildir            # Create Maildir directory for all new users

repeat for all existing user (eg. root):

maildirmake /root/Maildir

To use the password from /etc/courier/userdb (and not from PAM) (as root):

• Edit the file /etc/courier/authdaemonrc, and change it as follows:

authmodulelist="authuserdb"

• Restart the daemon:

/etc/init.d/courier-authdaemon restart

• Change the password for user $USER and commit the changes

/usr/sbin/userdbpw -md5 | sudo userdb $USER set systempw
sudo makeuserdb

• Test the new password with

nc imapserver 143
01 LOGIN username password
02 LOGOUT

Add a new user

• Let's create a new Linux user:

sudo adduser foo

• Now, we add it to userdb and set the password:

sudo su -
pw2userdb | grep -w foo >> /etc/courier/userdb
/usr/sbin/userdbpw -md5 | userdb foo set systempw
makeuserdb

Debian

Install (no ssl package):

sudo apt-get install courier-imap courier-doc

To fix FAM/Gamin issues:

sudo apt install gamin

Troubleshooting

Fix FAM/Gamin library issue

On Debian, we get the following error message when connecting to the server.

Filesystem notification initialization error — contact your mail administrator (check for configuration errors with the FAM/Gamin library)

The error seems due to the FAM library not working correctly on Debian [1], [2]. It can be replaced by Gamin:

sudo apt install gamin

OpenSUSE

• Uninstall the default IMAP server (UW IMAP) packages, or they'll create a conflict
• Install Courier IMAP package (packages courier-authlib and courier-imap).

Cygwin

See the page dedicated to Courier Cygwin.