You have a need to run a packet capture (tcpdump) on SMG.
Release : SMG 10.7.4 and later.
Component : Command line.
How to run a tcpdump on SMG:
tcpdump --port 25 --output capture01.cap
smg [10.8.1-7] tcpdump help
Usage: tcpdump [ --port port ] [ --ip ip_addr ] [ --output output_file_name ]