After PMPro checkout, if the purchase is a gift level send an email to the gift recipient.

pmpro_after_checkout_send_gift_certificate_email.php

/*
	Send Gift Certificate email at checkout.
	
	Requirements:
	1. Paid Memberships Pro
	2. The PMPro Gift Levels Addon
	3. Register Helper Add On with a "gift_certificate_email" field added via custom code.
*/
function pmpro_after_checkout_send_gift_certificate_email($user_id) {
	global $pmprogl_gift_levels, $pmpro_level, $wpdb;
	
	//which level purchased
	if(!empty($pmpro_level))
		$level_id = $pmpro_level->id;
	elseif(!empty($_REQUEST['level']))
		$level_id = intval($_REQUEST['level']);
	else
		return;	
		
	//gift for this? if not, stop now
	if(empty($pmprogl_gift_levels) || empty($pmprogl_gift_levels[$level_id]))
		return;
	
	//get the user's last purchased gift code
	$gift_codes = get_user_meta($user_id, "pmprogl_gift_codes_purchased", true);
	
	if(is_array($gift_codes))
		$last_code_id = end($gift_codes);
	
	if(!empty($last_code_id))
	{		
		$code = $wpdb->get_row("SELECT * FROM $wpdb->pmpro_discount_codes WHERE id = '" . intval($last_code_id) . "' LIMIT 1");		
		
		if(!empty($code))
		{
			$code_url = pmpro_url("checkout", "?level=" . $pmprogl_gift_levels[$level_id]['level_id'] . "&discount_code=" . $code->code);			
			$user = get_userdata($user_id);
			$to = get_user_meta($user->ID, 'gift_certificate_email', true);
			$email = new PMProEmail();
			$email->email = $to;
			$email->from = $user->user_email;
			$email->fromname = $user->display_name;
			$email->template = "gift_certificate";
			$email->subject = "Your membership to " . get_bloginfo('name') . ".";
			$email->body = "<p>Use this link to setup your membership: <a href=\"" . $code_url . "\">" . $code_url . "</a></p>";
						
			$worked = $email->sendEmail();			
		}			
	}
}
add_action('pmpro_after_checkout', 'pmpro_after_checkout_send_gift_certificate_email', 15);