Exim
exim is a popular mailserver. You can use the exim command to administer, get info from, and other interactions with the exim mailserver.
exim -Mvh messageID show email header for the specified message
exim -Mvb messageID show the body of the email
exim -Mvl messageID show the logs for the specified email
exim -bpc show the number of e-mails in the queue
exim -bp show the e-mails in the queue
exim -bt person@ example. com Sends a "test message" to the specified e-mail address. Kind of a "traceroute for exim".
exigrep grep for mail logs
Example:
exigrep spam@psygen.org /var/log/exim_mainlog