Please proceed with the security review of this new extension, aimed to be deployed in Wikimedia (T110170)
Repository: rENLT extension-Newsletter
Development status: T110642: Implement all the features required for running the Newsletter extension in Wikimedia & https://phabricator.wikimedia.org/tag/mediawiki-extensions-newsletter/
Test instance: http://newsletter-test.wmflabs.org/wiki/Special:Newsletters