Fix Courier "imap has failed" Error (FreeBSD on cPanel)

[Miraenda]

Issue:
Courier IMAP is not running on FreeBSD

Error:

imap has failed, please contact the sysadmin (result was 
"authdaemond is not running").

You might have the above when you either try to restart "IMAP Server (Courier/Dovecot)" in WHM or on issuing /scripts/courierup --force

Also, you will likely see the following in webmail clients (Roundcube, Squirrelmail, Horde):

Unexpected condition from IMAP server, closed or corrupt connection 
to IMAP. Possible mailbox corruption.

Two Possible Resolutions:
1. In /etc/rc.conf file, this line is missing:

courier_authdaemond_enable="YES"

The lines that should be present in /etc/rc.conf file for IMAP are these:

courier_authdaemond_enable="YES"
courier_imap_pop3d_enable="YES"
courier_imap_pop3d_ssl_enable="YES"
courier_imap_imapd_ssl_enable="YES"
courier_imap_imapd_enable="YES"

After adding the missing line and restarting IMAP, the service should then be working. If not, try another /scripts/courierup --force at that point.

2. /usr/ports/security/courier-authlib-base isn't installed properly

Run the following to rebuild it:

cd /usr/ports/security/courier-authlib-base
make deinstall && make install clean

Other possibilities are you need to re-install all the others as well:

cd /usr/ports/security/courier-authlib
make deinstall && make install clean
cd /usr/ports/mail/courier-imap
make deinstall && make install clean
/scripts/courierup --force