cPanel Email Error: "retry time not reached for any host after a long failure period"
This can be caused by a corrupt database file.
Fix it by running the following SSH commands as root:
cd /var/spool/exim/db rm -f retry retry.lockfile rm -f wait-remote_smtp wait-remote_smtp.lockfile service exim restart
or
/usr/sbin/exim_tidydb -t 1d /var/spool/exim retry > /dev/null /usr/sbin/exim_tidydb -t 1d /var/spool/exim reject > /dev/null /usr/sbin/exim_tidydb -t 1d /var/spool/exim wait-remote_smtp > /dev/null /scripts/courierup -- force /scripts/eximup --force