mail(string $to, string $subject, mixed $message, mixed $headers = '', mixed $attachments = array()) : mixed
Borrowed from WordPress
Send mail, similar to PHP's mail A true return value does not automatically mean that the user received the email successfully. It just only means that the method used was able to process the request without any errors.
Array or comma-separated list of email addresses to send message.
Subject of the email.
The body of the email.
Email headers sent.
Attachments to be sent with the email.