I'm guessing it works using push services which in my experience can take around 3 minutes for your recipient to receive the email (using gmail to gmail) - maybe using our apple ID's or a designated FaceTime email address helps to facilitate an immediate FaceTime connection. - I'm looking forward to finding out..
iPhone 4 (4.2.1) – Jailbroken & iPad 2. Using iOS for 4 years. Hate facebook, love last.fm. If you value any advice given in iLounge, come back and say "thanks".. :-)