New versions of MsgFiler Engine 1.2.9 and the Original MsgFiler Mail Plugin 2.3.4 have been released. The update for the Original MsgFiler Mail Plugin fixes a bug with filing when using the Return/Enter key. It also provides compatibility support for macOS Sierra.
It is common for macOS updates to disable your Mail plugins. To get back fast-filing performance with MsgFiler, simply:
- Download the latest version of the plugin.
- Decompress the ZIP archive.
- Double-click on the disk image file.
- Go to the Finder.
- Hold the option-key down and click on the Go menu.
- Choose Library.
- Navigate to the
~/Library/Mail/Bundlesfolder. - Drag the
MsgFilerEngine.mailbundleorMsgFilerPlugIn.mailbundlefolder into the Bundles folder. - Quit and relaunch Mail.
Verify that the plugin is active by clicking on the Message menu:
- MsgFiler Engine: A menu item labelled “MsgFiler Engine 1.2.8” will appear at the bottom of the Message menu.
- Original MsgFiler Mail Plugin: A menu item labelled “Move with MsgFiler” will appear at the bottom of the Message menu.
MsgFiler 
Thanks again! Updating MsgFiler is the very first thing I do after an update! I can’t imagine living without it.