//this variables is used to stop the function getting called too many times in quick succession
var mask_email_click_clock=0
//this variable stops firefox queuing up confirms
var mask_email_click_waiting=false
function check_email(email,input_location){
	if(
		email!=""
		&&
		/^(?!.*\.\.)[_a-z0-9+\.-]+@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/i.test(email)==false
	){
		var timeout=1500;//min time in ms between alerts
			var date=new Date()
			if(mask_email_click_clock==0 || date.getTime()-mask_email_click_clock>timeout){
				mask_email_click_clock=date.getTime()
				if(confirm("We think there may be an error in your email address.  You typed:\n"+email+"\nIf you'd like to edit it, click OK. If you're sure it's right, click Cancel and carry on.")){
					setTimeout(input_location+".focus();mask_email_click_waiting=false",1)
				}
			}
			date=new Date()
			mask_email_click_clock=date.getTime()
	}
}