http://www.courier-mta.org/authlib/
認証ライヴラリ

-----------------------------------------------------------
courier-authlib のインストール

$ tar xjvf courier-authlib-0.57.tar.bz2
$ cd courier-authlib-0.57
$ ./configure --with-redhat 
$ make
$ sudo su
# make install
# make install-migrate
# make install-configure
# exit
-----------------------------------------------------------
Courier-IMAP4.x のインストール

$ cd ../courier-imap-4.0.4
$ ./configure --prefix=/usr/local/courier-imap \
                         --enable-unicode=iso-2022-jp \
                         --with-redhat
$ make
$ make check
$ su
# make install
# make install-configure
-----------------------------------------------------------
認証用デーモン(authdaemon) の起動

/usr/local/sbin/authdaemond start
-----------------------------------------------------------

userdb を利用した認証

# useradd -s /bin/false imap4



IMAP_CAPABILITY="IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE AUTH=CRAM-MD5"

authdaemonrc の変更
# vi /usr/local/etc/authlib/authdaemonrc