I solved it, but uncovered a small issue.
To solve it:
1- New attribute: Contact.EmailAddressMailTo
2- Contact rule: Contact.EmailAddressMailTo='mailto:'+Contact.EmailAddress
3- In the Presentation tag for Contact.Email address, the hyperlink is "Determined by the contents of the tag": Contact.EmailAddressMailTo
Now the issue:
While clicking on an email address on the Presentation properly opens up a blank email in the user's email client, a blank browser window also opens up.
Tom