CUBE Contact 0.4.2-beta — Linux desktop build

A sealed-store mail client: IMAP + SMTP, multiple accounts with their own
folder trees, newsletter filing, local danger scan, drafts, per-account Sent.

New in 0.4.2-beta: unread mail is marked with a small green dot in the message
list

Also in this build: the sealed relay — switch it on per account from the
settings page and new mail for that mailbox arrives with its body sealed to
a key that exists only inside this app (no server-side body search or
recovery). Off by default.; opening a message clears the dot (the read state is kept in the sealed
store and pushed to the server with the read chip). 0.4.1-beta added the
mail-first window and the one search box that searches mail and pages.

Requires: a Linux desktop with GTK3 and WebKitGTK 4.1 (Debian 13 trixie ships
both). 90-day evaluation; a paid licence is installed from the mail settings
page or from a licence message.

Install:
  sh install.sh                 (into ~/.local)
  PREFIX=/usr/local sudo sh install.sh
Then start CUBE Contact from the menu, or run the command the installer prints.

Same licence as the Firefox extension: free 30-day trial, then $19 a year.
