SpamTitan - Comprehensive Email Protection. 99.99% Spam Detection. Blocks phishing, viruses, malware and other email threats.
Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
Sanebox - SaneBox is a cloud-based service that allows users to filter and manage their emails.
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
MailCleaner - Cloud & on-premise anti spam software for businesses
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates