Johan,
Resolved in case 86960 (bug fix) for 3.5 final - from Servoy support this am. Keystroke details can be found in this case submission.
The validation of the email string itself is fine. The problem is to do with entering invalid data into this field and then trying to remove it (ie - accidental entry of some data into the field and then deciding “I don’t want anything in this field”).
Michael