Installing and using postfix will give you ability to view mails processed by it:
# print a list of all queued mail mailq # print a particular message, by ID (you can see the ID along in mailq's output) postcat -vq [message-id] # process the queued mail immediately postqueue -f # delete ALL queued mail (use with caution—but handy if you have a mail send going awry!) postsuper -d ALL