VESmail is open source (Apache-2.0), written in C, and builds on Linux, macOS and Windows (MSYS2).

github.com/vesvault/VESmail
Releases & source tarballs

brew install vesvault/ves/vesmail

Install libVES (which needs OpenSSL, cURL and liboqs), then:

./configure && make && sudo make install

See the README for details, sample configs and daemon setup.

1. Start your instance — vesmail imap --tls and vesmail smtp --tls, or vesmail daemon with the sample configs.
2. Create your VES account — sign in to the Profile Manager with your email address. A new address receives a verification code, and you choose a VES PIN — that is the entire signup, there is no separate registration form.
3. Create your VESmail profile on the same page — your provider's IMAP/SMTP settings and credentials, end-to-end encrypted in VES. Supply your instance URL to verify the credentials through your own instance.
4. Set up your email client — the profile's Email App Setup section shows the username, the generated password (your VES App Key) and the host/port settings, with step-by-step instructions for common clients.