PHP mail stop working with Gmail on localhost site

Question

I developed a php solution to send a mail with gmail. It worked properly until yesterday but today I haven't been able to send mails with the function implemented.

sendmail.ini configuration:

[sendmail]
smtp_server=smtp.gmail.com
smtp_port=25
smtp_ssl=auto
error_logfile=error.log
auth_username=xxx@gmail.com
auth_password=xxx
pop3_server=
pop3_username=
pop3_password=
force_sender=xxxs@gmail.com
force_recipient=
hostname=

This is the part of the PHP code where I send the mail

        $mail="xxn@xxx.com";
        $titulo="title";
        $message='Message';
        $header="From: Sender <xxx@gmail.com>\r\n";
        $bool=mail($mail,$titulo,$message,$header);