mailsnarf outputs e-mail messages sniffed from SMTP and POP traffic in Berkeley mbox format, suitable for offline browsing with your favorite mail reader.
mail snarf is one of the tools included in the dSniff package of network security auditing tools. mail snarf is capable of reading email transferred to, and from, an ethernet network device. Use of mail snarf is limited to the LAN that the computer running mail snarf is on, unless used in conjunction with arpspoof.
mail snarf [-i interface | -p pcapfile] [[-v] pattern [expression]]
cyborg@cyborg:~$ mailsnarf -i eth0 mail snarf: listening on eth0