source: https://www.securityfocus.com/bid/297/info

NTMail v3.X is susceptible to being used as a mail relay for SPAM or other unsolicited email. Connecting to the mail server (tcp25) and issuing a 'mail from' command with <> as the data will allow an unathorized user to relay email via this server.

Gordano's own JUCE product (to prevent mail relay attacks and other SPAM activity) will not prevent NTMAIL v.3.x from being used as a mail relay.

Specify <> in the 'Mail From' field.