no S/MIME in 2023? I will not switch to a paid account.

It is so critical to be able to use S/MIME signature when sending messages. Many partners rely on that.

Just purchased Proton Mail, and I'm really upset to find that this is still not working. I assumed that any email provider would allow SMIME. Really disappointed.

The lack of this feature hinders me to switch my main email account to ProtonMail

PLEASE ADD THIS. it's totally ridiculous that this is not a feature. I am a paid user, and regretting it now that this is missing.

its 2022, why would this not be built in.

This is one of the most important features that Proton Mail is missing. I will have to use a different email provider if this doesn’t change soon.

I am using both, pgp and s/mime. It would really be helpfull if proton would support s/mime.

I receive S/MIME signed e-mail and just want to know if it is genuine or not.

Currently, Proton treats S/MIME the way most other email clients treat GPG: they act as if it does not exist.

This would be amazing! Please support this alongside PGP, ProtonMail :-)

How can protonmail call itself most secure and not have S/MIME support?

Yeah, please add this feature. :-)
(ProtonMail PLUS subscriber)

+3 (ProtonMail Visionary subscriber)

It would be really handy if I could sign with S/Mime, PGP/Mime is very niche and not widely adopted.

It would be useful for ProtonMail to have S/MIME support to sign messages. Apple Mail does it, Outlook IOS can read S/MIME signed messages and display a verified badge, as Apple does. Any timeline for this?

+3 I have been using S/MIME for over a year now. It is natively available on all my iOS devices by simply importing a .mobileconfig or .pcks profile. Likewise it's supported by Thunderbird on Windows out of the box. It doesn't get easier than that. What remains cumbersome is where or how to get a certificate/profile - same as with PGP.

I looked at PGP in the 90s as well, great to work with privately, but it's not supported natively by most applications. Quite frankly, if it's so difficult to integrate PGP (an add-on of sorts every time?) then it should exactly NOT be recommended for personal use, in my humble opinion.

SMIME is much more ubiquitous. Therefor, please reconsider adding SMIME support. No one is asking that you abandon PGP, but please add SMIME? Many will appreciate it, you may even win new users.

+3 please implement this... I agree PGP works great if the other end is also on ProtonMail, otherwise S/MIME looks practically only way to sign an email as not many have set up PGP already.

+1 (ProtonMail Visionary subscriber)

While I love PGP, it remains.a niche.

Nowadays, even Gmail — both free and G-suite — supports S/MIME digital signatures in received emails (Gmail doesn't support S/MIME fully-encrypted emails instead, but this is not the point). When the sender uses a valid S/MIME signature, Gmail will say that the sender is verified by a public CA and the email message has not been compromised.

I don't understand why Protonmail refuses to do the same. It doesn't have to support full S/MIME encryption: recognizing valid S/MIME signatures would be great!

I would love to see this feature for message authentication and encryption.

Yes please, this is big. The vast majority of companies that routinely use encryption use S/MIME, not PGP. (Barring maybe newer security-focused companies, but good luck communicating with government using PGP.) Someone recently asked me to send them a document with personal information encrypted using their S/MIME key. When asked if they had a PGP public key, they had no idea what PGP even was. This is the general response I get. At this point, PGP (while great) is mostly still for tech savvy people. Even in 2020 PGP is a PITA to setup for most people not using ProtonMail. ;-)