..........JETGO are investigating as to how this email eventuated.
Forget the email!
Start with how do you recruit someone/ people capable of this level of unprofessional conduct.
As a management team, ask yourselves how did you manage to let this happen?
AND, most of all, DO NOT attempt to water down this person's complaint with the email was UNSIGNED & sent by an unauthorised person. Its a company communication, it is unprofessional and its from Jetgo! Own it!