Fixing Sidekick for Apple Mail on OSX El Capitain and later

Update: the below no longer works (as of ~2018?) given the Sidekick rebrand (to Hubspot Sales) and Apple Mail’s plugin lockdown. Sidekick is one of the best mail utilities out there. Especially on OSX, combining the power of Apple Mail, and the possibility to track your email opens, it’s one of my favorite apps. Unfortunately, the Hubspot […]