John Floren

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Posted 2023/7/7

ProtonMail Rewrites Your Emails

I switched to ProtonMail a few years back after getting fed up with Google. It’s been mostly acceptable, but a few months ago the Android client started mangling emails – if I hit “send” too soon, it would send out only part of what I’d typed; I had to wait 10 seconds or so after I finished typing before hitting send to be sure it sent. I figured I’d switch to some other email client instead, since I wasn’t particularly in love with the Proton app anyway.

My solution was to set up the Proton Bridge in a VM on my NAS, then used rinetd to forward incoming connections on the IMAP and SMTP ports to the bridge (which only listens on I then set up tailscale on that box and on my phone; with that, I could connect any Android email client (I like FairEmail) to my Proton account. I was also accessing it from Linux using Claws.

Everything was great until I decided the other day that I’d also like to do PGP signing on my outgoing messages. I exported a signing-only subkey to my Android device and configured FairEmail+OpenKeyring to use it, then I also set up Claws on Linux for PGP/MIME.

When I sent a test message to myself, though, Claws and FairEmail didn’t have any clue that it was signed. If I switched to PGP inline, it worked. I sent an email to one of the Claws maintainers, who reported that my MIME structure was all messed up. He sent me a signed message back, and Claws was able to verify the signature just fine.

It turns out that Proton has been breaking outgoing PGP signatures from the beginning:, It seems that their argument is this:

It’s absurd that there’s no way to disable this, no option to tell Proton “if you see a multipart/signed or multipart/encrypted message, just leave it the hell alone.”

I’m looking at other potential email hosts. I know PGP isn’t widely used, but I have a hard time swallowing Proton’s silent mangling of my email, and I especially dislike their smarmy we-know-better attitude when people complain about it.