Add an option in the settings to protect the main e-mail address from being leaked. When this option is turned on and I accidentily send an E-Mail which would reveal the default/main e-mail to the recipient the server would not send that e-mail and notify me that I need to use a reverse alias. Additionally, I think it would be nice to be able to select e-mails that differ from the main/default e-mail for protection, as some people might have multiple addresses they would want to protect from leaking.