How to remove a Mail plugin without opening Mail
I'm using a particular Mail plugin which has been very useful up until now. However this plugin has just been updated with the result that Mail won't open and the error message I get refers to a problem with the HockeySDK which I see this plugin has just installed. I'm waiting to hear from the developer about this but in the meantime I can't use Mail on my Mac. Since I can't open Mail I can't remove the whole plugin in the normal way. Is there another way I can remove this plugin in the meantime until this problem is sorted out?
iMac, OS X El Capitan (10.11.6), MacBook Pro. iPhone 6, iPad Air 2