As a rule, do not send romantic or sexually explicit emails from the office. At most companies your email can be read by anyone in the IT department once you hit "send."
Also, beware the life-long embarrassment factor if you inadvertently fire off a romantic email to your boss, rather than your crush, from the company address book. It happens. For less exposure when communicating with your honey, always use your personal email address, such as Yahoo or Gmail. Better yet, sit down and craft an old-fashioned love letter.