BurnFeed Email Subscription plugin allows you to show Google Feedburner subscription form either as a floating button or in sidebar of your website.

A MailPro API interface to add email addresses into a MailPro address book

Feedburner Follow Me plugin allows you to show Google Feedburner subscription form either as a floating button or in sidebar of your website.

Your Real-Time Audience Engagement Platform Beyond Emails & SMS. Engage with your WordPress website's audience through web push notifications.