I have recently had to wipe my Mac and restore using Migration Assistant. The only issue I have found since is that Apple Mail plug-ins are not showing for activation in Mail Preferences. I have tried un-installing and reinstalling the SpamSieve Apple Mail plug-in, and it’s showing in ~Library/Mail/Bundles, however nothing in Apple Mail Preferences to actually activate. This is the same situation with a couple of other Mail plug-ins too.