http://community.elgg.org/discussion/view/857958/sending-emails-with-elgg

start.php

elgg_register_event_handler('init', 'system', 'custom_blog_notification_init');

function custom_blog_notifier_init() {	
	
	//Register an event listener to send email when blog is created
	elgg_register_event_handler('publish', 'blog', 'custom_blog_notification_send');
}

/**
 * Callback function to send a notification
 * 
 * @param type $event Equals 'publish'
 * @param type $type  Equals 'blog'
 * @param type $blog  ElggEntity of subtype 'blog'
 */
function custom_blog_notification_send($event, $type, $blog) {
	
	$subject = "New blog: $blog->title";
	$body = $blog->description;
	
	$user = $blog->getOwnerEntity();
	$from = "$user->name <$user->email>";
	
	$to = "someone@somewhere.com";
	
	elgg_send_email($from, $to, $subject, $body);
	
	return true;
}

Thanks so much for your update. I'v been trying to implement it on my site but it doesnt seem to be sending any email. I modified the "someone@somewhere.com" to my email. Is there something I'm getting wrong? The plugin just has start.php, and a manifest file.