dmarc-srg utilizes sendmail for outbound mail. Setup sendmail to send mail before continuing.
Setup dmarc-srg mailer variables
$mailer = [
'from' => 'dmarc-reports@example.com',
'default' => 'me@example.com'
];Test summary_report.php
php -f /var/www/dmarc-srg/utils/summary_report.php format=html domain=all period=lastmonth