If remote user is sending using an authenticated SMTP session, you would find his name within chkuser logging.
Look at these entries from my smtpd log:
@40000000425d6a992de7abbc.s:@40000000425d6a2c106b451c CHKUSER rejected rcpt: from <::> remote <fusion.fast-servers.net:unknown:220.127.116.11> rcpt <[EMAIL PROTECTED]> : not existing recipient
@40000000425d6a992de7abbc.s:@40000000425d6a250b7faffc CHKUSER rejected rcpt: from <::> remote <mx03.scottish-southern.co.uk:unknown:18.104.22.168> rcpt <[EMAIL PROTECTED]> : not existing recipient
rcpt: from <::> have no user name. Is that the right place for this information.
What I'm missing?
Thanks, -- Walter.