This is a Magento extension called mass email. With this Magento extension, you can send emails to a number of your Magento store users at together. Just select users or ‘select all users ‘ and click on the mass email. Now the form will ask for email subject, email body, and site admin email address.
This email extension provides you WYSIWYG editor for your email content. You can add anything to your email body.This extension also provides place holders like [customer.firstname], [customer.lastname], [customer.email] which will replace with registered user name email etc when the email is sent.
After download extension Please follow Use documentation for how to use it file for how to install this extension in Magento.
This extension works in following Magento versions: