When users connect to any public Internet access, they really may not know who might be between them and the recipient of the email or data stream they are creating. For this reason, Tech Target suggests that using a VPN is something that WAN managers need to consider and explain to their road warriors.
“Most of the protocols and applications used send information via cleartext. Services such as email, Web and FTP are not designed with security in mind and send information with few security controls and no encryption. If your road warriors are not using a VPN (virtual private network) when they connect to their wireless hotspot, their information can potentially be exposed to any nearby hacker, cracker or criminal.”