so the problem is: I have a mailto html tag and when used via IE8 (our clients use it...), before popping up outlook, it shows a warning "This form is being submitted using e-mail. Submitting this form will reveal your e-mail address to the recipient, and will send the form data without encrypting it for privacy. You may continue or cancel this submission". The problem is that many of the users do not speak english, so our client wants us to either remove this message (we explained them it is a browser constraint, but they still insist on doing it) or translating it to bulgarian. Any ideas which of these is easier to do ? (I mean possible at all). Is there a way to turn this message off from the browser?
You cannot get rid of the message -- as you already said, it is a browser constraint, and entirely outside of your control.
The only way to get rid of it would be to rewrite your site to send the message via a different method. But that's overkill just to get rid of a warning message.
For the record, this isn't an IE8 issue; you'll get the same message under newer IE versions as well (I've seen it myself recently in IE11).
The real question is if your users are Bulgarian, why are they getting English messages from their browser? They should be running Windows and IE localised to their language. If they do that, then the message will show up in Bulgarian.