Example: Overide the PHPMailer object in WordPress

phpmailer_action.php

<?php

add_action( 'phpmailer_init', 'fw_prepare_email' );
function fw_prepare_email( $phpmailer ) {

		$host = get_option('fw_tools_smtp_host');
		$port = get_option('fw_tools_smtp_port');
		$login = get_option('fw_tools_smtp_login');
		$password = get_option('fw_tools_smtp_password');
		$from = get_option('fw_tools_from_address');
		$force_from = get_option('fw_tools_force_address');
		$from_name = get_option('fw_tools_from_name');
		$force_name = get_option('fw_tools_force_name');

		if (empty($host) or empty($login)) {
			return;
		}
	    
	    if ( ! is_object( $phpmailer ) ) {
	        $phpmailer = (object) $phpmailer;
	    }
	    if ($force_from) {
	    	if ($from == '') {
	    		return;
	    	} else {
	    		$phpmailer->From = $from; 
	    	}
	    } else {
	    	$dom_org = substr($phpmailer->From, strpos($phpmailer->From, '@') + 1);
	    	$dom_set = substr($from, strpos($from, '@') + 1);
	    	if ($dom_org != $dom_set) {
	    		$phpmailer->From = $from; 
	    	} 
	    }
	    if ($force_name) {
	    	if ($from_name == '') {
	    		return;
	    	} else {
	    		$phpmailer->FromName = $from_name; 
	    	}
	    } else {
	    	if ($phpmailer->FromName == '') {
	    		if ($from_name != '') {
	    			$phpmailer->FromName = $from_name; 
	    		} else {
	    			$phpmailer->FromName = get_option('blogname');
	    		}
	    	} 
	    }
	    $phpmailer->Mailer     = 'smtp';
	    $phpmailer->Host       = $host;
	    $phpmailer->SMTPAuth   = true;
	    $phpmailer->Port       = $port;
	    //$phpmailer->SMTPDebug = 1;
	    $phpmailer->Username   = $login;
	    $phpmailer->Password   = $password;
	    $phpmailer->SMTPSecure = 'tls';
	}