WP Mailster is the first WordPress plugin that comes with all the features user know from mailing list software like Mailman and Listserv. This plugin allows you to run a discussion mailing list. That means your users are part of a group and communicate by email without having to log into a website. Every email sent to a central email address is forwarded to the rest of the members of the list. When members reply to such emails WP Mailster again forwards them to all the other list recipients. Unlike newsletter plugins this allows true two-way communication via email. Features include:

group communication through email usable with any POP3/IMAP email account recipients are managed by the admin in the WordPress admin area users can subscribe/unsubscribe through widgets on the website all WordPress users can be chosen as recipients, additional users can be stored users can be organized in groups single users or whole groups can be added as recipients of a mailing list replies to mailing list posts can be forwarded to all recipients (or only the sender) email archive for browsing the mails full support of HTML emails and attachments many more features