https://support.cpanel.net/hc/en-us/articles/360051894014-Clear-Exim-Retry-DB-to-bypass-retry-time-not-reached-after-fixing-an-issue-with-delivery
/usr/local/cpanel/scripts/exim_tidydb
mv -vi /var/spool/exim/db/retry{,.$(date +%s)}
mv -vi /var/spool/exim/db/retry.lockfile{,.$(date +%s)}
/scripts/restartsrv_exim