Use mailto link on contact summary emails if outbound email is disabled

We're using CiviCRM with outbound mail set to Disabled. When visiting a contact, our users see a clickable link on the e-mail address of the contact.
Clicking the link opens a popup to send a new e-mail.

When clicking Send Email, the message "Outbound mail has been disabled. Click Administer >> System Setting >> Outbound Email to set the OutBound Email." is displayed.
The mail has not been send (which is good, since outbound mail is disabled), and the mail contents is lost, hence the Major priority.

Proposed solution:
When outbound mail is disabled, the link should not open a popup, but instead launch the default mail client (using a mailto: link).