I have been working on scripts to help me administer email servers.
This works pretty well on Postix/Debian server to search logs for sent emails. You can even use grep to search the reasults ie. /root/bin/search-sent-emails.sh |grep domain-name.
log='/var/log/mail.log'
grep "status=sent" $log | \
egrep -ve 'postfix/(cleanup|pickup|master|qmgr|smtpd|local|pipe)' | cut -f1 -d"(" |sed 's/relay=.*//' |sed 's/delay=.*//' |sed 's/delays=.*//' |sed 's/dsn=.*//'
It could use some fine tuning. How do I add zcat to search older log files like /var/log/mail.log.2.gz etc.