Module rules 

Mail filters: what a message shows, and what is then done to it on its server (docs/client.md, “Filters”).

A filter holds conditions, each a field, a test and a value (“From contains @bank.example”), all of them needed or one enough; and actions: into a folder, to the archive, to spam, flagged, read, to the trash, a keyword. One flat list serves every account, each filter on all of them or on some, in the configuration ([[mail.filter]]), shared with it. Filters run on what arrives unread in an inbox, on whichever device fetches it first (sioul-sync’s filters), and on the rest of the inbox when you ask. The Mail page’s search reads the same conditions (Condition::matches on a Message).

Text is compared as Sioul’s search compares it: case and accents aside (text::fold_char), each run of spaces one space. A sender nothing authenticates is read as nobody’s: a condition on who sent it holds for no such message, as a project’s route does not (docs/porch.md, “Trust”).

At the end, Virtual Secretary’s words (docs/virtual-secretary.md): the folder it moved a message to becomes a proposal here (FolderMapping).

Structs

Choice

One choice the editor offers: its id and its words.

Condition

One condition: a field, a test, a value.

Facts

What a condition knows of a message beyond its card, given by whoever asks.

FieldForm

A field as the editor offers it: its tests, and what each asks for.

Filter

One filter: its conditions, what it does, on which accounts.

FolderMapping

Virtual Secretary, compatibility mode A: it keeps sorting on the server; the IMAP folder it moved a message to becomes a proposal here.

Form

Everything the filters’ editor offers, in your language.

Message

A message as conditions read it: its card and the facts beside it, each field folded once, when a condition first asks for it.

Person 🔒

One address of a message, folded.

Place

Where a message is and its marks, for the search’s own conditions (Field::Account, Field::Folder, Field::Mark): a filter has none.

Plan

What the filters do to one message, once added up: the first filter that moves it says where it goes; reads, flags and keywords add up.

TestForm

Enums

Act

What a filter does to a message that matches, on its server.

Destination

Where a filter sends a message.

Field

What a condition reads of a message.

Join

Every condition, or one of them.

Proposed

What Virtual Secretary’s sorting proposes for a message.

Shelf

Test

How a condition compares its field with its value.

Value

What a condition’s value is, for the editor to ask it.

Constants

DAYS

The days of the week as a condition names them, Monday first.

FILTERED

The keyword that says filters went through a message: set on its server before they act on it, so that another device fetching it too leaves it alone (sioul-sync’s filters).

KEPT 🔒

The characters of a card’s text kept beside it (card::EXCERPT_LIMIT): one shorter holds the whole text; one this long may be cut.

KINDS

The kinds of attachment a condition names.

MARKS

The marks a search’s condition names (Field::Mark): “is not read” is unread.

ROLES

The folders a search’s condition names by purpose (Field::Folder), whatever their name on each server; Gmail’s “All Mail” is its archive.

WHO

Who a sender may be to you, as a condition names it: “known” is anyone in your address books or on a list (safe, neutral or restricted). The blocked are not among them: their mail is set aside, and no filter touches it.

Functions

addresses 🔒

The addresses of a header (To, Cc, Reply-To), their names decoded.

attachment_kind

The kind of an attached file, by its type, else by its name’s ending (KINDS; “other” for the rest).

day 🔒

A day as a condition writes it: “2026-10-01”.

days 🔒

Days of the week as a condition writes them (“sat,sun”): their places from Monday (0), in order.

facts_of

The facts beside a message the Porch judged: who its sender is to you, and whether anything proves it is them.

fold

Text as conditions compare it: case and accents aside, each run of spaces one space, trimmed.

folder_named

Whether a folder condition’s value (a purpose of ROLES, or a server’s own name) names a folder of role and name.

form

The editor’s words.

holds

Whether all conditions hold (Join::All), or one (Join::Any). None never holds.

is_on 🔒

joined 🔒

Words joined: “Saturday or Sunday”; “Monday, Tuesday or Friday”.

keyword

Whether name can be an IMAP keyword a filter adds (RFC 9051 §2.3.2, an atom): no space, no ( ) { % * " \ ], no control character; never a system flag, the spam keywords (the spam action sets those) nor Sioul’s own mark.

lenient

Reads the filters of the configuration one by one: one that does not read is left out, never the whole configuration with it.

on 🔒

plan

What filters do to message, which came to account: each filter that runs on that account and matches, in their order, until one that stops the rest.

plans

What filters do to each message the Porch judged, for its account; none for what it protects (untouched), nor where no filter matches.

said_size 🔒

A size in words: “5 MB”, “500 KB”, in your language’s units and decimals.

size

A size as a condition writes it, in bytes: “5 MB”, “500 KB”, “1.5 Go”; megabytes when it says no unit.

time 🔒

A time of day as a condition writes it: “18:00”, “8:30”.

untouched

Whether the Porch keeps a message from every filter: set aside (forged, blocked, a borrowed name, your provider’s spam), hostile, in your spam filter’s review queue (it moves or flags that mail itself), or a code you asked for, which must reach you where you look for it.

who_is 🔒