Missing e is a browser add in that makes tumblr even more awesome with added features as an extension. tumblr forced them to remove it from download but everyone with it already installed could keep it! tumblr had issues with its api usage and it broke api rules and they demanded changes. There was a huge petition to save it and bring it back! tumblr keeps mysteriously pulling third party software. missing e did break rules but also tumblr is starting to get more and more heavy handed with 3rd party software! most of it actually improves the tumblr experience!
Missing e is now back online with a new version which meets all of tumblrs demands. If you already have the old add in (the best version frankly), its up to you if you update or not. If you do update you lose the time stamps and when it tells you who unfollowed you. Some settings which really drained the api have gone. By updating you will lose those old features just to warn you. But its great its back in a modified way!
This is the 3rd script that I used that tumblr have suddenly got all heavy over and pulled! the other two authors never came back with unblocked versions :(