Unable to send test emails

I get a critical error why trying to send a test email.

Fatal error: Uncaught Error: Call to undefined method NewsletterEmails::send_test_email() in /wp-content/plugins/newsletter-autoresponder/admin/edit-email-composer.php:40 Stack trace: #0 /wp-content/plugins/newsletter-autoresponder/admin/edit.php(16): include() #1 /wp-content/plugins/newsletter-autoresponder/admin/index.php(7): include(‘/home2/…’) #2 /wp-content/plugins/newsletter-autoresponder/plugin.php(550): require(‘/home2/…’) #3 /wp-includes/class-wp-hook.php(324): NewsletterAutoresponder->{closure}(”) #4 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(”, Array) #5 /wp-includes/plugin.php(517): WP_Hook->do_action(Array) #6 /wp-admin/admin.php(259): do_action(‘newsletter_page…’) #7 {main} thrown in /wp-content/plugins/newsletter-autoresponder/admin/edit-email-composer.php on line 40
There has been a critical error on this website.

Any clues?

• This topic was modified 5 hours, 2 minutes ago by pwizard.

The page I need help with: [log in to see the link]