[Telemakhos]

While I'm sure some of these flaws also apply to S/MIME, I feel like its client support (even in Apple iPhone native mail app) is far superior to PGP. Apple made S/MIME installation and use across its ecosystem, and I remember it being easy in kMail once upon a time when I used KDE; why didn't S/MIME ever catch on?

[p2detar]

It did, but on enterprise level. S/MIME uses the CA hierarchical trust model, which is centrally managed and much more compatible with how internal enterprise structures are built. In a large enterprise you would have IT managing your AD/CS and therefore also managing the issuing, revocation and so on of employee certificates. But for the public this model of management isn't really practical.

[bigfatkitten]

I've worked in an org that used S/MIME heavily.

In a managed environment, you also get the advantage of certificates stored in a central directory (LDAP etc), and so certificate selection for the client is seamless.

All you have to do is hit "encrypt" in your mail client, enter your smart card PIN and the machine does the rest.