Exim Errors: T=remote_smtp defer (-53): retry time not reached for any host

 T=remote_smtp defer (-53): retry time not reached for any host

If exim logs report this error then the most likely cause for this issue is corruption of exim databases, specially if it reports this error for each email. To resolve this issue following steps can be done using one of exim database tools ‘exim_tidydb’ :

/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

After performing above steps, run the following Cpanel scripts :
/scripts/courierup -- force
/scripts/upcp --force