This example uses tcpdump. In order to record a conversation
you need to specify a large enough buffer with the "-s" option or
else you will miss some or all of the packet payload.
# tcpdump -w /file/name -s 2000 host example.com and port 25
Run this for a while, stop with Ctrl-C when done. To view the
data use a binary viewer, or ethereal, or use my tcpdumpx
utility that is available from