ConvertPlus allows you to integrate your own addon for different mailers. Apart from the mailer addons integrated by ConvertPlus, a new mailer could be integrated as stated below.

For your addon to work you need to create a wordpress plugin with defining your class in it – Lets say addon name is MyAddon, the class name would be as shown below –

if(!class_exists('Smile_Mailer_Myaddon')){
	class Smile_Mailer_Myaddon{
		private $slug;
		private $setting;
	}
	new Smile_Mailer_Myaddon;	
}

See to it that the name Smile_Mailer_Myaddon matches.
The variables $slug, $settings are defined in constructor as shown below –

function __construct(){
	require_once('lib/your_api_files.php');
	add_action( 'admin_init', array( $this, 'enqueue_scripts' ) );
	add_action( 'wp_ajax_get_myaddon_data', array($this,'get_myaddon_data' ));
	add_action( 'wp_ajax_update_myaddon_authentication', array($this,'update_myaddon_authentication' ));
	add_action( 'wp_ajax_disconnect_myaddon', array($this,'disconnect_myaddon' ));
	add_action( 'wp_ajax_myaddon_add_subscriber', array($this,'myaddon_add_subscriber' ));
	add_action( 'wp_ajax_nopriv_myaddon_add_subscriber', array($this,'myaddon_add_subscriber' ));
	$this->setting  = array(
		'name' => 'MyAddon',
		'parameters' => array( 'api_key' ),
		'where_to_find_url' => 'https://link_showing_api_key',
		'logo_url' => plugins_url('images/logo.png', __FILE__)
			);
	$this->slug = 'myaddon';
}

Here include your API libraries (if any).

require_once('lib/your_api_files.php');

This action does the basic operations of adding your addon to ConvertPlus Third Party Mailer list dropdown. Also custom javascript files are added in this action.

add_action( 'admin_init', array( $this, 'enqueue_scripts' ) );

These actions does the operation to get lists from mailer, disconnect mailer, add a subscriber, authenticate mailer, etc.

add_action( 'wp_ajax_get_myaddon_data', array($this,'get_myaddon_data' ));
add_action( 'wp_ajax_update_myaddon_authentication', array($this,'update_myaddon_authentication' ));
add_action( 'wp_ajax_disconnect_myaddon', array($this,'disconnect_myaddon' ));
add_action( 'wp_ajax_myaddon_add_subscriber', array($this,'myaddon_add_subscriber' ));
add_action( 'wp_ajax_nopriv_myaddon_add_subscriber', array($this,'myaddon_add_subscriber' ));

This is the most important part. These are the class variables that define the mailer slug and other settings. Please be careful while declaring these variables.

$this->setting  = array(
	'name' => 'MyAddon',
	'parameters' => array( 'api_key' ),
	'where_to_find_url' => 'https://link_showing_api_key',
	'logo_url' => plugins_url('images/logo.png', __FILE__)
);

All the parameters mean as listed below:

This slug should be kept in small cases. All the functions/actions should match this slug. For example:

$this->slug = 'myaddon';

Now add this below code as it is, things would work properly, since this is $settings & $slug, dependent operations:

/*
* Function Name: enqueue_scripts
* Function Description: Add custon scripts
*/
		
function enqueue_scripts() {
	if( function_exists( 'cp_register_addon' ) ) {
		cp_register_addon( $this->slug, $this->setting );
	}
	wp_register_script( $this->slug.'-script', plugins_url('js/' . $this->slug . '-script.js', __FILE__), array('jquery'), '1.1', true );
	wp_enqueue_script( $this->slug.'-script' );
			add_action( 'admin_head', array( $this, 'hook_css' ) );
}

/*
* Function Name: hook_css
* Function Description: Adds background style script for mailer logo.
*/


function hook_css() {
	if( isset( $this->setting['logo_url'] ) ) {
		if( $this->setting['logo_url'] != '' ) {
			$style = '<style>table.bsf-connect-optins td.column-provider.'.$this->slug.'::after {background-image: url("'.$this->setting['logo_url'].'");}.bend-heading-section.bsf-connect-list-header .bend-head-logo.'.$this->slug.'::before {background-image: url("'.$this->setting['logo_url'].'");}</style>';
			echo $style;
		}
	}
			
}