As described by Sean and by Halamka with the Direct Project any medical Provider with an EHR that offers a Direct email account, can send secure email messages to a patient.
I am going to demo it with my Care360 EHR account:
First type a message to the patients Direct email or his regular email. When you don't know your patient Direct email on Healthvault you just send an email to firstname.lastname@example.org with a subject line containing the patient's existing email account. I also attached to the message the patient's Continuity of Care Document (CCD).
The patient John Doe will get a regular email from you:
Then the patient will sign to his HealthVault account or create one
My patient John Doe can now see my Care360 EHR message and also his Continuity of Care Document (CCD).
Patient John Doe can decide or not to add the CCD to his HealthVault account
The CCD sent from Care360 EHR looks like this on HealthVault:
These are really very exciting times in healthcare :-)