Swift Mailer - multiple recipients not working - php

Question

I have a problem with Swift Mailer, It seems easy, but I'm strugling with it for hours.
I need to send an email to multiple recipients.
This is a string I begin with (the content of $email->getRecipients() ):
// Just an example
first#gmail.com, second#gmail.com
First I remove all non-visible characters:
$string = preg_replace('/[\x00-\x1F\x7F]/u', '', $email->getRecipients());
Then I add surranding quotes:
$addQuotes = "'" . str_replace(",", "','", $string) . "'";
And remove empty spaces:
$recipients = str_replace(' ', '', $addQuotes);
Which gives me:
'first#gmail.com','second#gmail.com'
If I paste the string manually:
->setTo(['first#gmail.com','second#gmail.com'])
It works. But when I try to put variable like this:
$array = explode(',', $recipients);
...
->setTo($array)
Emails are not being sent.
When I do this:
->setTo([$recipients])
I get the error Address in mailbox given ['...','...'] does not comply with RFC 2822, 3.6.2.
I also tried:
foreach($array as $recipient) {
$message->setTo($recipient);
$this->get('mailer')->send($message);
}
Not working! But again, if I paste string directly, it works:
foreach($array as $recipient) {
$message->setTo('first#gmail.com');
$this->get('mailer')->send($message);
}
The code:
private function sendEmail($email)
{
//$email->getRecipients() = 'first#gmail.com, second#gmail.com'
$string = preg_replace('/[\x00-\x1F\x7F]/u', '', $email->getRecipients());
$addQuotes = "'" . str_replace(",", "','", $string) . "'";
$recipients = str_replace(' ', '', $addQuotes);
$array = explode(',', $recipients);
$message = \Swift_Message::newInstance()
->setSubject($email->getSubject())
->setFrom($email->getSender())
->setTo($array)
->setBody(
$this->renderView(
'Emails/default.html.twig',
array('body' => $email->getBody())
),
'text/html'
);
//foreach($array as $recipient) {
// $message->setTo($recipient);
// $this->get('mailer')->send($message);
//}
$this->get('mailer')->send($message);
}