Yii mail() expects parameter 1 to be string, array given

How can I convert array to string?

$to=Person::model()->findAll($criteria);

I want to send an email to multiple email addresses.

mail($to,$model->subje开发者_StackOverflow中文版ct,$model->body,$headers);

If $to only contains email addresses you could convert it to a string: $to = implode(', ', $to);