erplibre/doc/EMAIL.md
Mathieu Benoit 16aecc2d33 [ADD] mail: read and send email from the TODO CLI
An IMAP/SMTP client in the menu, with its tests against real servers. Most
of the work went into refusals: an application password is named only when
the server actually refuses, an accented password is reported as never
having left the machine, and a refusal is recognised by what the server
SAYS rather than by matching its wording. A malformed date no longer takes
the whole folder down, and a received email is never read as markup.

--- FR ---

Un client IMAP/SMTP dans le menu, avec ses tests contre de vrais serveurs.
L'essentiel du travail porte sur les refus : le mot de passe d'application
n'est nommé que lorsque le serveur refuse vraiment, un mot de passe accentué
est signalé comme n'ayant jamais quitté la machine, et un refus se reconnaît
à ce que le serveur DIT plutôt qu'à ses mots. Une date illisible n'emporte
plus le dossier entier, et un courriel reçu n'est jamais lu comme du balisage.

Assisted-by: Claude Opus 5
2026-08-16 03:56:34 -04:00

16 KiB

Mail client

A mail client built into the TODO CLI: several accounts, IMAP + SMTP, and a local cache — so you can read and answer email without leaving ./script/todo/todo.py.

Every Mail > ... path below is shorthand for TODO > [3] Assistant > [2] Mail - Read and send email > ... — the full path is spelled out once, in "Adding an account".

Prerequisites

Four Python packages, already listed in requirement/erplibre_require-ments.txt (the .venv.erplibre environment, not an Odoo venv):

  • cryptography — seals the local cache in encrypted and ephemeral mode.
  • keyring — the system keyring, one of the two places a password can live.
  • pykeepass — the KDBX vault, the other place, and the one the client tries first.
  • textual — the terminal UI itself. Without it, "Open the mail client (TUI)" prints a message and does nothing; the rest of the menu (accounts, sync, cache) still works.

Install them with:

.venv.erplibre/bin/pip install -r requirement/erplibre_require-ments.txt

App passwords for Gmail, Outlook and iCloud

Phase 1 speaks plain IMAP/SMTP login only — no OAuth yet (that is phase 2). Gmail, Outlook and iCloud have all closed that door to the account's real password, so each of these three presets requires an app password instead:

Provider Where to generate it
Gmail Enable 2-step verification, then myaccount.google.com > Security > App passwords
Outlook / Microsoft 365 account.microsoft.com > Security > Advanced security options > App passwords
iCloud account.apple.com > Sign-In and Security > App-Specific Passwords

Use that generated password when account setup asks for one — never the account's normal password. The "Standard server" preset (generic IMAP/SMTP) does not need one.

Adding an account

Menu path: TODO > [3] Assistant > [2] Mail - Read and send email > [2] Accounts > [2] Add an account.

The prompts, in order:

  1. Short account name — becomes both the folder name under ~/.erplibre/mail/ and the vault reference, so it cannot contain / or start with a dot.
  2. Email address.
  3. Display name (optional) — shown in the From: header as Display Name <email>.
  4. Provider — a number from the printed list: Gmail, Outlook, iCloud, or "Standard server" (generic IMAP/SMTP).
  5. If you picked "Standard server", the IMAP host and SMTP host are asked next; the other presets fill these in for you.
  6. If the preset requires an app password, its note is printed here as a reminder.
  7. Password — typed hidden (getpass), then stored — never written to accounts.json.

Where the password goes: at the password step, the client hands off to the CLI's shared KDBX manager — the same one already used for the OpenAI key and Odoo credentials. It reads kdbx.path / kdbx.password from the TODO config (script/todo/todo.json, overridable in private/todo/todo_override.json / private/todo/todo_override_private.json). If kdbx.path isn't set yet, a graphical file picker pops up asking you to choose an existing .kdbx file — it needs a display, and cancelling it (or running headless) fails account creation with "le fichier kdbx n'a pas pu être ouvert" (French — see Troubleshooting). Set kdbx.path (and kdbx.password, to skip the prompt) before adding your first account, pointing at a .kdbx vault you already have (create one with KeePassXC or similar). The system keyring is only ever used for an account whose secret_ref already points at one — the menu itself always writes new accounts into the KDBX vault.

accounts.json (at ~/.erplibre/mail/accounts.json) only ever holds a secret_ref such as kdbx:ERPLibre/Mail/perso — a pointer, never the secret. It is safe to read, edit by hand, or check into a private backup.

The three cache modes

Every account keeps a local cache — a small SQLite database plus one file per downloaded message — so the inbox stays readable offline. Three modes control what that cache leaves on disk:

Mode What's on disk Encryption key
clear (default) ~/.erplibre/mail/<account>/cache.db and .eml files, readable as plain text none
encrypted same location, but sender, recipients, subject, snippet, message-id and message bodies are sealed with AES-256-GCM generated once, stored in the vault next to the password (.../cache-key)
ephemeral under /dev/shm/erplibre-mail-<pid>/<account>/ (or the system temp dir if /dev/shm isn't writable), sealed the same way as encrypted generated fresh in RAM at every run, never written anywhere, and the whole directory is removed when the session closes

Even in clear mode, the technical fields the SQL needs to sort and filter — UID, folder, date, flags, size — are always plain; only the person-identifying fields (and the message body) are ever sealed, and only in encrypted/ephemeral.

Set the general default at Mail > [4] Cache > [1] Default cache mode; it is the mail_cache_mode preference (default clear). Override it per account at Mail > [4] Cache > [2] Cache mode of one account — this writes the account's cache_mode field in accounts.json; leaving it at null there means "inherit the general default."

Mail > [4] Cache > [3] Cache size and purge lists every account's effective mode and disk usage, and can erase one account's cache entirely (after confirmation) — the next sync rebuilds it from scratch.

The TUI

Mail > [1] Open the mail client (TUI) opens a three-pane screen: an account/folder tree on the left, the message list in the middle, and a preview pane on the right, with a status line at the bottom.

Key Action
↑ ↓ Tab move within a pane / move focus between panes (Textual defaults)
h open the help window: every shortcut plus a few notes, closed with Escape
z toggle full-screen preview (hides the folder tree and the message list)
Escape leave full-screen
v cycle the layout: columns, split, stacked
+ / - grow / shrink the pane that has focus
0 back to the default pane sizes
r sync the account of the currently selected folder (all its folders)
Shift+R sync every account
/ open the search field (filters the currently visible list only — locally, over subject/from/to/snippet; it does not search the server)
s / u mark the selected message seen / unseen
c compose a new message
a / Shift+A reply / reply all
f forward
w save the message's first attachment to ~/Téléchargements (created if missing)
n add an account without leaving the client
l show the tail of ~/.erplibre/mail.log and this session's sync errors
q quit

This table is written by hand and can fall behind the code; the h window cannot. It builds its list from the application's own key bindings every time it opens, so it is the reference if the two ever disagree.

The bars between the panes can also be dragged with the mouse, and pane sizes are remembered per layout.

The footer's key hints, like the help window, follow the CLI's chosen language, as do the account tree, the message list and the preview text.

Writing a message

c opens the compose form: To, Cc, Subject, an Attachments field (semicolon-separated file paths — a comma is legal in a filename, so only ; splits entries; there is no file picker, type the paths), and a multi-line body. e sends the body out to $EDITOR (or nano if unset) and reads it back; if the editor is missing or exits with an error, the body you had is kept untouched. Ctrl+S (or the Send button) delivers the message; Escape discards the draft — there is no save-as-draft.

a (reply) and Shift+A (reply all) prefill To/Cc/Subject/ In-Reply-To/References and quote the original message in the body. f (forward) prefills the Fwd: subject and attaches the original message automatically, as a message/rfc822 attachment; the body itself starts empty — write your own note above the attached original.

Reply, reply-all and forward all need the original message's body available — from the cache, or fetched live if the account is online; with neither, you get "No message selected." / "No message to forward."

Sending requires the account to be online (composing offline fails with "Account offline: cannot send." — there is no offline outbox). Once sent, a copy is filed into the account's Sent folder over IMAP; if that filing step fails, the status line says so, but the message has already left — it is not resent.

Synchronization

A sync pass is incremental: only UIDs above the last known one are fetched, message bodies are never downloaded during a pass (only headers), and bodies are fetched on demand when you open a message. Flags (read/unread, etc.) of already-known messages are re-checked on every pass, so a message read elsewhere shows up correctly here too.

Sync happens:

  • At launch — opening the TUI kicks off one background sync of every account.
  • On demand — r (current account) / Shift+R (all accounts) inside the TUI, or Mail > [3] Synchronise now from the CLI menu (prints a per-account summary to the terminal).
  • Automatically, every mail_refresh_sec seconds (default 300 = 5 minutes; 0 disables it) — but only while the TUI is open. Close it and the timer goes with it; nothing syncs in the background afterward.

If the server reports a changed UIDVALIDITY for a folder (its UIDs no longer mean what they used to — typically after a server-side migration), that folder's cache is purged and resynced from scratch automatically; there is currently no on-screen notice when this happens beyond the folder briefly emptying and refilling.

Where the files live

Path Contents
~/.erplibre/mail/accounts.json account list — servers, presets, cache mode, and a secret_ref pointer; never a password (mode 0600)
~/.erplibre/mail/<account>/cache.db that account's SQLite cache (mode 0600, parent directory 0700)
~/.erplibre/mail/<account>/<folder>/<uid>.eml (or .eml.enc when sealed) one file per downloaded message body
/dev/shm/erplibre-mail-<pid>/<account>/ an ephemeral account's cache while the process is alive; removed when it exits (a sweep at every startup also clears directories left behind by a killed process)

Troubleshooting

Error messages raised by the mail package itself (secrets.py, store.py, crypto.py, accounts.py, smtp_send.py, imap_transport.py, imap_sync.py) now go through the CLI's translation layer, the same as the menu prompts and TUI labels: running the CLI in English shows them in English. The wording below is quoted in French, this document's reference language; expect the matching English wording when EL_LANG=en.

"Connection failed: ..." when adding or testing an account. Mail > [2] Accounts > [5] Test an account connection prints the server's exact error and then asks for the password again — up to 3 attempts. The password in the vault is only overwritten after a successful connection, so a typo never destroys a working password. If the account is Gmail, Outlook or iCloud, check first that you used an app password (see "Prerequisites" above), not the account's normal one. Opening the TUI itself does not retry automatically: an account with a rejected password gets a ⚠ marker; if it had synced successfully before, its already-cached folders stay visible and readable, they just stop refreshing — only a brand-new account (nothing synced yet) shows no folders at all. Either way, go run "Test an account connection" to fix it.

"le fichier kdbx n'a pas pu être ouvert" when adding an account. The shared KDBX vault isn't configured yet, its file picker was cancelled, or the CLI is running without a display to show that picker. Set kdbx.path (and kdbx.password) as described in "Adding an account" above, then try again.

"le trousseau du système écrirait le mot de passe en clair (backend ...)". keyring's active backend isn't one of the ones known to actually encrypt — this happens over SSH, in a container, or on a machine with no desktop session, where keyring silently falls back to a plaintext file store. The client refuses rather than pretend that's safe. Use the KDBX vault instead (see above), or run somewhere a real keyring is unlocked.

"Install textual for the mail client (pip)." textual isn't installed. Mail > [1] Open the mail client (TUI) just prints this and returns; every other menu entry (accounts, sync, cache) still works without it.

The folder cache says it changed (UIDVALIDITY). Nothing to do — the client purges and resyncs that folder by itself the next time it syncs. Expect the message list to empty briefly and refill.

"cache illisible, purgez-le et resynchronisez : ...". The account's cache.db is corrupt. Mail > [4] Cache > [3] Cache size and purge may itself fail to open the same broken file; if so, delete the account's cache directory by hand and resync:

rm -rf ~/.erplibre/mail/<account>/

Testing against a real server

Almost every mail test uses an in-memory double. A double only produces what its author imagined, which is how three protocol bugs reached users. So there is also a sandbox: a real IMAP server (Twisted) and a real SMTP server (aiosmtpd) that a test starts on an ephemeral loopback port, talks to over real TCP, and kills when it finishes — pass or fail.

The point is not conformance. A well-behaved server proves little; this one can misbehave on purpose. A test declares the exact bytes a message is made of — raw 8-bit header bytes, an unknown-8bit charset — and can drop the connection or refuse a command mid-sync. Adding a new hostile behaviour is a small subclass in test/mail_sandbox.py, not a new server.

These tests do not run in the fast loop. Without twisted and aiosmtpd the whole file skips visibly. Run them deliberately:

.venv.erplibre/bin/python -m unittest discover -s test \
    -p test_mail_live_server.py -v

What it does not cover, and will not pretend to:

  • SPECIAL-USE — Twisted announces only IMAP4REV1 NAMESPACE IDLE. The bug where a sent message was filed under a guessed folder name instead of the one the server announced is therefore out of reach. Implementing the extension in the sandbox would only test our own assumption about it, which is the exact failure this sandbox exists to escape.
  • No provider quirk — Gmail's label-as-folder model, Microsoft's OAuth, Apple app passwords: none of it is exercised. The sandbox is a plain RFC 3501 server, not a stand-in for a specific provider.
  • No TLS — the sandbox talks in the clear on 127.0.0.1. starttls and ssl code paths are not exercised here.
  • Nothing leaves the machine — no external host, no OS keyring, no ~/.erplibre, no real credentials, and never a fixed port.

Phase 1 limits

  • No OAuth — Gmail, Outlook and iCloud need an app password (see above); OAuth is phase 2.
  • No statistics — no read/unread counters or activity dashboards beyond the per-folder unseen count shown in the folder tree.
  • No server-side search — / filters only what's already synced to the local cache.
  • No offline outbox — sending requires the account to be online; there is no queue that flushes once you're back online.

See the design spec for what the following phases add.