Scheduling API

Link SMTP Pro can queue email for later delivery with automatic retry. From your own code or another plugin:

if ( function_exists( 'lsmtp_can' ) && lsmtp_can( 'scheduling' ) ) {
    LSMTP_Pro_Scheduler::enqueue(
        'user@example.com', 'Subject', 'Body', '', array(), time() + 3600
    );
}

A cron job dispatches due messages every 5 minutes and retries failures up to three times.