Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
Twicca - Twicca is a Twitter client for Android that is simply awesome. Features: * Notification
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
Tweetbot - Sync your timeline across your iPhone, iPad, and Mac. Mute tweets by user, hashtag, tweet source, or keywords (including regex). 3rd Party support for image, video, read later, and timeline sync services.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Tweedle App - Notion is nice but sometimes all you need is an app like Tweedle.