Uninstall GPG/PGP email plugins (as of May 2018)

In May 2018, it was revealed that the commonly used encrypted email protocol PGP (Pretty Good Privacy) was vulnerable to a certain sophisticated cyber attack. This is unsurprising in a way, since PGP has been around for decades. For protection, you should uninstall any PGP plugins in emails clients like Apple Mail and Mozilla Thunderbird.