function emailCheck(emailStr){
  var pattern=/^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\.([a-zA-Z])+([a-zA-Z])+/;
  if(pattern.test(emailStr)){         
    return true;  
  }
  else{   
    alert("Invalid email address entered. Please check your email address and try again");
    //txtEmail.focus()
    return false;
  }
}