When I enter the e-mail address for the e-mail subscription, the popup window disappears and I return to the site home page. When I say sign up for the newsletter again, “Thanks, your registration request was successful! Please check your e-mail inbox to confirm.” i see your warning
When you sign up with a popup it disappears automatically. If you do not want to show the popup after successful signup Go to MC4WP > Form > click on the settings tab > Form behaviour > Select “yes” to hide the form fields after a successful sign-up. Also check the plugin settings.
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