There are several newsletter plugins for Drupal which make reaching out to your followers much easier. These plugins may even be used to replace the standard Drupal Mail to enable customization of all the admin mails, registration confirmation, and other announcement mails according to the theme of the rest of your website. These plugins can use other modules to send HTML mails as well as Text encodings. Some of these plugins also have the ability to send separately edited, theme based mails to separate user groups according to your preferences. There are some plugins which can be used to even build a newspaper online and can double up as newsletter plugins which can divide issues into separate sections, topics and subtopics.
Even your followers can subscribe to periodic newsletter mails from your website if you install these plugins. There are plugins which are exclusively dedicated to handle all the response mails to subscriptions. So these plugins can be set to send out mass emails to a category of viewers of your website. All of these plugins can support multiple schedules such as daily, monthly, or customized further. These plugins also extend the API of the Drupal core for other convenient solutions, also provides a CRUD controller in addition to that. They come with their own widgets and formatters and auto-integration options with views, metadata and feeds. In addition to the common features some also come with tools for statistical user analysis. Most of these plugins work best with Drupal 6 and above.