function validateRequiredField(field, message){
	val = field.value.replace(/^\s+|\s+$/g,'');
	if(val==''){
		alert(message);
		field.focus();
		return false;
	}
	return true;
}

function validate(){

	if(!validateRequiredField(document.emailForm.name,'Please enter your name')) return false;
	if(!validateRequiredField(document.emailForm.phone,'Please enter your telephone number')) return false;

	//validate email
	if(!(/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/.test(document.emailForm.email.value))){
		alert('Please provide a valid email address');
		document.emailForm.email.focus();
		return false;
	}
		
	//validate post code
	if(!validateRequiredField(document.emailForm.postcode,'Please enter your post code')) return false;
	
	//validate make
	if(!validateRequiredField(document.emailForm.make,'Please enter the vehicle\'s make')) return false;
		
	//validate model
	if(!validateRequiredField(document.emailForm.model,'Please enter the vehicle\'s model')) return false;
	
	//validate year
	if(!validateRequiredField(document.emailForm.year,'Please enter the vehicle\'s year of manufacture')) return false;
	
	//validate mot expiry
	if(!validateRequiredField(document.emailForm.mot,'Please enter the vehicle\'s MOT expiry date (past or present)')) return false;
	
	//validate problems
	if(!validateRequiredField(document.emailForm.problems,'Please enter a description of the vehicle and indicate any problems')) return false;
				
	return true;
}