Before you pursue any of these methods, consider the threat model.
If you need a true offline client that lives entirely on a USB drive, you must use a bridge. Note that this requires a . proton mail desktop app portable
is a small application that decrypts your Proton emails on the fly and serves them to any local email client via localhost. The Bridge itself is not easily portable (it installs a service), but you can pair it with Portable Thunderbird . Before you pursue any of these methods, consider
or a cloud-synced folder—and leaves no trace on the computer once it's closed. is a small application that decrypts your Proton
: Some users utilize community-maintained wrappers or tools like the Wavebox desktop client , though these often still require installation and may not be officially supported for portable use.
Users seeking a zero-install experience on shared computers should use the Proton Mail web app
If you need a portable solution for Proton Mail, consider these alternatives: