function isValidEmail(s)
	{
		var reg1 = new RegExp('^[a-zA-Z0-9][a-zA-Z0-9@._-]{3,}[a-zA-Z]$');
		var reg2 = new RegExp('[@.]{2}');
		
		if (s.search(reg1) == -1
				|| s.indexOf('@') == -1
				|| s.lastIndexOf('.') < s.lastIndexOf('@')
				|| s.lastIndexOf('@') != s.indexOf('@')
				|| s.search(reg2) != -1)
			return false;
		
		return true;
	}