Similar to programs like Mailman or Listserv this extension allows you to run a discussion mailing list.

That means that 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 Mailster again forwards them to the other list recipients.

Mailster allows your users to be part of a group and communicate by email without having to log into your Joomla site.

This is primarily made with discussion email lists (two way communication) in mind, although Mailster can also be used for newsletters.

Features
- For Group communication and newsletters
- Usable with any POP3/IMAP email account
- Recipients are managed by the admin in the backend
- Users can (un)subscribe with frontend plugin or module (optional)
- All Joomla 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
- Mail archive for browsing the mails
- Full support of HTML emails and attachments
- Seamless installation: all plugins are included and are installed automatically
- English, German, French, Dutch, Italian, Danish, Japanese and Slovenian translation included
- many more features

Designed for all...
- users that are tired of group messaging systems that require another login
- users who want to communicate with their favourite mail client
- admins that are tired of updating personal details on different systems
- admins who want to be able to use users within Joomla as recipients of a mailing list

Changelog
** Version 1.7.4 Bugfix Release (June 13th, 2022) **
- Improve styling in Joomla 4 (email archive status of emails)
- Fix handling of certain binary attachments
- Fix issue in subscribe / unsubscribe forms in the URL rewrite mode
- Fix to hide inactive lists from subscribe/unsubscribe modules
- 5 more fixes and improvements

** Version 1.7.3 Bugfix Release (December 16th, 2021) **
- Fix installation time problem introduced in 1.7.2 (mailing lists got deactivated but not reactivated)

** Version 1.7.2 (December 10th, 2021) **
- Support longer passwords, list names and subject prefixes (previous limit was 45 characters, now increased to 191)
- Improve the user interface for the user edit view
- Fix Joomla 4 incompatibilities (subscriber plugin, error handling)

** Version 1.7.1 (November 7th, 2021) **
- Fix performance issue in emails archive (pagination inefficiency)
- Fix frontend archive (mails / threads views) to work with Joomla 4

Version 1.7.0 (November 5th, 2021)
- Joomla 4 compatibility (Joomla 3.x still supported)
- Turn off opportunistic STARTTLS for imap_open
- Fix situations where the mailbox connection was not working
- 3 more fixes and improvements

Version 1.6.0 (May 3rd, 2021)
- PHP 8 compatibility
- Joomla 2.5 is no longer supported in order to prepare for the coming Joomla 4
- Fix email charset problem leading to plus letters being omitted
- Do not add mail recipients to queue when already moderated (approved) message gets approved again

Note that this version has limitations (e.g. max. 50 recipients per list) compared to our commercial products Mailster Essential, Business and Ultimate. Find a feature comparison overview here: http://www.brandt-oss.com/index.php/mailster/pricing