Send Template Email to Custom object email field

Well Recently I was figuring it out to send email to a custom object email field through the list view page custom button. On click of the button it should open a small panel to select the Email Template and send it to the selected email.

Hmm pretty cool panel. But how to do it?
This is how I started,

1) Create a global class as follows. (Note :- You need to replace the "Person_Detail__c" object with your custom object and the "Email__c" field with your custom email field)

	global class SendEmailHandler {
	webservice static boolean sendEmail(List<Id> personIds,string templateId)
	{
	//Get all the Persons record where Id in personIds and email not equal to null
	List<Person_Details__c> lstperson = [Select Id, Name, email__c from Person_Details__c where Id in :personIds and email__c != null];
	//Get the Contact Id to set it for setTargetObjectId of SingleEmailMessage
	List<Contact> lstContact = [Select Id from Contact limit 1];
	Messaging.SingleEmailMessage[] emailMessageList = new Messaging.SingleEmailMessage[]{};
	//Loop through the Person record and Fill the EmailMessage List
	for(Person_Details__c p : lstperson)
	{
	Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
	List<String> toaddress = new List<String>();
	toaddress.add(p.Email__c);
	mail.setToAddresses(toaddress);
	mail.setSenderDisplayName('MyCompanyName');
	mail.setTemplateID(templateId);
	mail.setTargetObjectId(lstContact[0].Id);
	mail.saveAsActivity = false;
	mail.setWhatId(p.Id);
	emailMessageList.add(mail);
	}
	//send the email with appropriate template to the person
	Messaging.sendEmail(emailMessageList);
	return true;
	}
	}

view raw SendEmailHandler hosted with ❤ by GitHub

2) Created a List View button named "Send Email" on your custom object with content source as "onclick Javascript" option

3) Below is the Javascript code for the button. (Note:- In my case I used "Person_Detail__c" as custom object. You need to use your custom object instead of "Person_Detail__c")

	{!REQUIRESCRIPT("/soap/ajax/19.0/connection.js")}
	{!REQUIRESCRIPT("/soap/ajax/19.0/apex.js")}
	{!REQUIRESCRIPT('//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js')}
	{!REQUIRESCRIPT('//ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.min.js')}
	function appendTags(){
	if(jQuery('[id=start-theme-css]').length==0){
	jQuery('head').append(
	'<link ' +
	'id="start-theme-css"' +
	'rel="stylesheet"' +
	'href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/themes/start/jquery-ui.min.css"' +
	'type="text/css" />'
	);
	jQuery('body').append(
	'<div id="dialog-confirm" title="Send Mass Email">' +
	'<p style="text-align:justify">' +
	'<img src="/s.gif" alt="Contact" class="pageTitleIcon" title="Contact" style="margin: 0 7px 30px 0"/>' +
	'Please select an email template to use.' +
	'<br/><br/>Email Template:<br/>' +
	'<select id="email-template" style="width:380px"></select>' +
	'</p>' +
	'</div>'
	);
	}
	}
	function createPopupWindow(){
	jQuery(function() {
	jQuery( "#dialog-confirm" ).dialog({
	resizable: false,
	width: 400,
	modal: true,
	show: {
	effect: "fade",
	duration: 500
	},
	hide: {
	effect: "fade",
	duration: 500
	},
	buttons: {
	"Send Mail":
	function() {
	sendMail();
	},
	Cancel:
	function() {
	jQuery( this ).dialog( "close" );
	}
	}
	});
	});
	}
	function fetchEmailTemplates(){
	var emailTemplates =
	sforce.connection.query(
	'SELECT Id, Name FROM EmailTemplate',
	{
	onSuccess:
	function(result){
	var records = result.getArray('records');
	var innerHtml = '<option value="">--Select--</option>';
	for(var i=0; i<records.length; i++)
	innerHtml +=
	'<option value="' + records[i].Id + '">' +
	records[i].Name +
	'</option>';
	jQuery('[id=email-template]').html(innerHtml);
	},
	onFailure:
	function(error){
	alert('An Error has Occurred. Error: ' + error);
	}
	}
	);
	}
	function sendMail(){
	var perIds = {!GETRECORDIDS( $ObjectType.Person_Details__c)};
	var templId = jQuery('[id=email-template]').val();
	var flag = sforce.apex.execute("SendEmailHandler", "sendEmail", {personIds:perIds,templateId:templId});
	if(flag)
	{
	jQuery("#dialog-confirm").dialog( "close" );
	alert('Your emails have been sent successfully');
	}
	}
	appendTags();
	fetchEmailTemplates();
	createPopupWindow();

view raw Send Mass Email hosted with ❤ by GitHub

That's it, now click on the "Send Email" button and send cool template emails to your recepients..