RustBox 0.2.3

RustBox is a webmail derived from c0h1b4/oxi. The consumed Oxi revision is recorded in UPSTREAM_BASE.

The repository is one Cargo application. The RustBox browser interface lives under src/web/, uses HTML/CSS/vanilla JavaScript, and is embedded into the Rust executable at build time. There is no TypeScript, React, Next.js, Node.js or Bun build step.

Layout

rustbox/
├── Cargo.toml
├── build.rs
├── src/
│   ├── main.rs
│   ├── ui.rs
│   └── web/
│       ├── index.html
│       ├── js/
│       │   ├── manifest.txt
│       │   └── *.js
│       ├── icons.svg
│       └── css/
├── migrations/
├── tests/
├── examples/
├── docs/
├── packaging/
├── scripts/
├── config.dev.toml
├── config.example.toml
├── UPSTREAM_BASE
└── dev.sh

build.rs combines the CSS modules from src/web/css/manifest.txt and JavaScript modules from src/web/js/manifest.txt. Cargo embeds the generated CSS/JS bundles, HTML and SVG sprite in the RustBox executable. There is no standalone source src/web/app.js; src/web/ is the single source of truth and Cargo generates the embedded bundles in OUT_DIR.

Storage and search in 0.2.3

RustBox separates three concerns: SQL metadata, blob storage and search. The SQL engine does not decide whether data_dir may be used. A single-node PostgreSQL/MySQL deployment may still use filesystem blobs and local Tantivy. In cluster mode, local node state is rejected unless the configured backend is explicitly shared.

Blob backends:

• storage.backend="filesystem" — local disk in single-node mode; set storage.shared=true only for a real shared POSIX mount such as NFS, CephFS or GlusterFS.
• storage.backend="s3" — AWS S3 or compatible APIs such as MinIO/Ceph RGW.

Search backends:

• search.backend="local_tantivy" — single-node.
• search.backend="opensearch" — cluster-capable. Index mutations are written first to a durable per-tenant SQL outbox and processed with retry/backoff/dead-letter handling.
• search.backend="disabled" — no full-text index.

In a cluster using shared SQL + S3/shared POSIX + OpenSearch/disabled search + pgp_enabled=false, data_dir is not required as persistent node state. See docker/README.md for ready Compose variants.

Configure mail servers

Mail endpoints are configured by the administrator, not on the login screen. Users enter only email and password.

Edit config.dev.toml before the first run:

default_theme = "system" # system | dark | light
default_interface_skin = "rustbox" # rustbox | gmail | proton | zoho | outlook | fastmail | apple-mail | yahoo | hey | nord | github | gitlab | discord | slack | reddit | notion | ...
log_level = "info" # trace | debug | info | warn | error | off; RUST_LOG overrides it
# Mail hosts may be omitted: IMAP defaults to localhost:993 and SMTP to localhost:587.
# imap_host = "localhost"
# smtp_host = "localhost"
tls_enabled = true
# tls_verify = true # omitted: false only for localhost/loopback, true for remote hosts
# Upload limit for one raw attachment.
max_attachment_size_mb = 10
# Hard limit for the complete rendered RFC822/MIME message submitted to the MTA.
max_message_size_mb = 50

# Optional features exposed by the server/UI.
sieve_enabled = true
diagnostics_enabled = true
about_enabled = true
# Adds CSP/frame/referrer/permissions/COOP response headers when enabled.
security_headers_enabled = false

# Optional; defaults to imap_host. Ignored when sieve_enabled=false.
# sieve_host = "mail.example.com"
sieve_port = 4190
sieve_tls_mode = "starttls"
sieve_allow_insecure_auth = false

# Optional administrator-owned headers added to every outgoing message.
# Structural/MIME headers such as From, To, Subject and Content-Type are rejected.
outgoing_headers = [
  "X-Company-Mailer: RustBox",
]

If the mail host settings are omitted, RustBox uses localhost with IMAP 993 and SMTP 587. TLS is enabled by default. Certificate and hostname verification are skipped automatically only for localhost/loopback unless tls_verify is set explicitly.

Mail-size limits are intentionally separate. max_attachment_size_mb applies to each raw uploaded file, while max_message_size_mb is checked against the final RFC822/MIME byte stream immediately before SMTP submission. The latter therefore includes message bodies, headers, MIME boundaries, base64 expansion, inline CID parts and OpenPGP transformations. The composer displays only an estimate; the server-side final-MIME check is authoritative.

Database, storage, search and cluster traffic

database_backend = "sqlite" | "mysql" | "pgsql" selects only the authoritative SQL database. It does not force or forbid local blob/search storage. In particular, PostgreSQL/MySQL are valid in a single-node installation together with storage.backend="filesystem" and search.backend="local_tantivy".

session_backend = "database" stores sessions in the selected SQL database. session_backend = "redis" moves only session persistence to Redis/Redis Sentinel. Mailbox metadata and cached message bodies remain in SQL.

data_dir is persistent node state only when a selected local feature actually needs it: default SQLite, implicit filesystem storage, implicit local Tantivy, or local OpenPGP keys. In cluster mode it is not required when those features are replaced with cluster-safe backends. Cluster validation is capability-based:

• SQL: shared MySQL/PostgreSQL; SQLite is rejected;
• blobs: S3-compatible storage, or filesystem with storage.shared=true on a real NFS/CephFS/GlusterFS mount;
• search: OpenSearch or disabled; local Tantivy is rejected;
• OpenPGP: remains disabled until a cluster-safe key backend exists;
• all nodes use the same session_encryption_key.

Example stateless cluster:

database_backend = "pgsql"
database_url = "postgres://rustbox:secret@db/rustbox"
session_backend = "database"
session_encryption_key = "<shared-key>"
cluster_mode = true
pgp_enabled = false

[storage]
backend = "s3"
bucket = "rustbox"
region = "eu-central-1"
# endpoint = "https://s3.example.com" # MinIO/Ceph RGW/etc.

[search]
backend = "opensearch"
urls = ["https://opensearch.example.com:9200"]
required = true

Shared POSIX is also supported without S3:

[storage]
backend = "filesystem"
path = "/mnt/rustbox-shared"
shared = true

Existing attachment files can be migrated to the configured storage backend without deleting the source files:

rustbox storage migrate --from filesystem:/old/data/root --to configured --dry-run
rustbox storage migrate --from filesystem:/old/data/root --to configured --verify

The SQL row is switched to the logical object key only after upload and size/checksum verification. Search state is rebuildable from SQL:

rustbox search reindex

Ready Docker examples are in docker/: standalone SQLite, PostgreSQL + SILO (S3-compatible) + OpenSearch, and MySQL + NFS + OpenSearch.

All executable application SQL is centralized by dialect under src/queries/{sqlite,mysql,pgsql}/queries.rs. The squashed compatibility baseline remains V046; RustBox 0.2.1 adds runtime migration V047 for attachment checksums/logical blob keys and the durable search outbox. The next migration number is V048. See migrations/README.md.

Development

Requirements: Rust toolchain with Cargo. OpenPGP key generation/sign/encrypt/decrypt is implemented with rPGP. Changing the passphrase of an existing private key additionally requires GnuPG (gpg) on the server; override the executable with RUSTBOX_PGP_GPG_BINARY if needed.

./dev.sh

Then open:

http://127.0.0.1:3001

To use another configuration:

RUSTBOX_CONFIG=/path/to/rustbox.toml ./dev.sh

Normal Cargo commands work from the repository root:

cargo run
cargo test
cargo build --release

UI

RustBox uses a compact three-pane mail layout: folders, message list and reader. The current internal baseline includes configurable special IMAP folders, collapsible folder hierarchy, folder CRUD/subscriptions, move/copy/bulk actions, drag-and-drop message moves, collapsible threads, raw headers/source download, labels, advanced/saved search, quota warnings, contacts/groups/vCard, calendar/ICS import, identities/signatures with automatic reply identity selection, HTML/plain/Markdown compose modes, CID inline images, and ManageSieve raw + visual rule editing with negation, dynamically addable conditions/actions and nested AND/OR chaining. OpenPGP includes per-user key management, identity binding, PGP/MIME + inline sign/encrypt/decrypt/verify, WKD/HKP discovery and private-key passphrase management.

IMAP IDLE events are delivered to the browser over the embedded WebSocket endpoint for realtime refresh and optional desktop notifications. Notification preferences include sound, folder selection and Do Not Disturb hours.

Appearance preferences are persisted per account and include light/dark/system theme, density, preview position, UI scale, multiple color presets, custom accent/background/panel/text colors, font, row height, pane widths, radius, contrast and visibility toggles. Administrators can set the global light/dark mode with default_theme = "system" | "dark" | "light" and the global interface style with default_interface_skin = "rustbox" | "gmail" | "proton" | "zoho" | "outlook" | ... in TOML. The global interface style is used on the login screen and by accounts set to Global default. Built-in interface styles include RustBox, Roundcube variants, Clean, Graphite, High contrast, Gmail/Proton/Zoho/Outlook/Fastmail/Apple Mail/Yahoo/HEY/GitHub/GitLab/Discord/Slack/Reddit/Notion-inspired profiles, Nord and Minimal. Predefined styles can optionally unlock the per-account UI scale control. The mailbox toolbar also exposes persisted date/sender/subject/size sorting, and remote images can be restricted to saved contacts.

The native RustBox interface intentionally uses flat surfaces, small radii and one SVG icon set. Compatibility skins may reproduce upstream visual treatments such as gradients, while toolbar icons remain SVG rather than Unicode glyphs.

ManageSieve

Supported modes:

• starttls — recommended;
• implicit — TLS immediately after connect;
• none — plaintext transport; reusable credential authentication remains blocked unless sieve_allow_insecure_auth = true is explicitly enabled.

When sieve_host is not configured, RustBox uses the authenticated session's IMAP host. Sieve uses the same session credentials; passwords are not exposed to the browser after login.

Native installation

./scripts/build-release.sh
sudo ./scripts/install-systemd.sh
sudo systemctl enable --now rustbox
sudo journalctl -u rustbox -f

For public access put an HTTPS reverse proxy in front of RustBox. The production example binds to 127.0.0.1:3001.

Following Oxi

Initialize Git after extracting the release archive:

git init
git add .
git commit -m "RustBox 0.2.3 release"
./scripts/setup-upstream.sh

Inspect newer Oxi changes:

./scripts/oxi-status.sh

Import the mapped Oxi backend delta:

./scripts/sync-upstream.sh

Oxi backend/... paths are mapped into RustBox's flat Cargo tree. Oxi frontend sources are never copied. Relevant upstream frontend behavior is reviewed and reimplemented in src/web/. UPSTREAM_BASE advances only after ./scripts/finish-upstream.sh completes review and the build gate.

To port one backend commit without advancing the baseline:

./scripts/oxi-port-commit.sh <oxi-commit>

See docs/UPSTREAM.md for details.

Attribution

See NOTICE.md. The supplied Oxi snapshot did not contain an authoritative LICENSE file; verify the exact upstream licensing terms before public redistribution.