FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Developed by FollowUp.cc
License: Commercial
Followup.cc is primarily focused on email tracking and follow-up management, making it ideal for individual users looking for simplicity and effectiveness in managing their emails. InStream, on the other hand, offers a wider range of features including reporting, analytics, and team collaboration tools, making it more suitable for organizations that require comprehensive email management solutions.