Threadsy has been discontinued. Similar sites and apps include Zimbra Desktop, which is free for personal use. Other options are iRedMail, Unified Inbox, Fuser and Boxbe. In total there are five Calendar Apps like Threadsy for Linux, Mac, Windows and self-hosting.
The free Zimbra Desktop client allows you to meld the online and offline worlds – storing and synching your email, calendar, contacts, files and documents in the cloud, yet having them locally accessible when on the road.
United States
A fully fledged, free email server solution, an open source project (GPL v2).
Use official binary packages from Linux/BSD distributions, with both i386 and x86_64 support.
Easy, fast deployment in LESS THAN 1 MINUTE. View YouTube Video to check how easy it is.
Works on both no.
Unified Inbox is a cloud based unified communication & social collaboration platform that centralizes external conversations, social engagement and internal team collaboration into one single experience across desktop and mobile devices
Singapore
The Fuser Chrome Extension makes checking and taking action on your new email and social updates.
Boxbe is a web-app that may know its users better than they know themselves. By tracking the emails that its users send and receive on a daily basis, Boxbe can effectively screen messages in a way that is both intelligent and accurate.
