I have offered to provide a written reference for a friend of mine who is applying for a new job. I have been given an email address to send the completed reference form to, which is a personal email address (firstname.lastname@example.org) as opposed to a generic corporate address (email@example.com). Neither of us are sure what sex the person is as the name is unisex and neither of us have spoken to this person directly.
Based on this post I thought the best way to address the email would be Dear Sir or Madam, however after reading the email back I felt it could be taken offensively.
Should I go with something less risky like To whom it may concern or am I overthinking the issue? I just felt Sir or Madam was a more appropriate address.