# RustBox features
RustBox is a self-hosted webmail for any standards-compliant IMAP/SMTP server. It ships as one Rust executable with the whole interface built in. The interface is available in English and Polish.
## Contents
- [Mail](#mail)
- [Composing](#composing)
- [Search, labels and contacts](#search-labels-and-contacts)
- [Filters (Sieve)](#filters-sieve)
- [Calendar](#calendar)
- [Notifications and realtime](#notifications-and-realtime)
- [Appearance](#appearance)
- [Mobile](#mobile)
- [Security and privacy](#security-and-privacy)
- [Administration and deployment](#administration-and-deployment)
- [Known limitations](#known-limitations)
## Mail
- Three-pane layout (folders, message list, reader) with resizable panes. The preview can sit on the right or at the bottom, or be turned off.
- Folder tree with subfolders shown under their parent and collapsible branches. You can create, rename, delete and subscribe to folders, mark all as read and empty a folder.
- Special folders (Sent, Drafts, Trash, Junk, Archive) are configured per account. They follow renames, and administrators can set server-wide defaults.
- Accurate total and unread counters, kept in sync with the mail server. Changes appear immediately and are reconciled in the background.
- Threaded or flat reading, previous/next navigation, and automatic opening of the next message after a move or delete.
- Bulk actions on many messages at once, including the whole search result: read/unread, flag, archive, move, copy, label, spam and delete.
- Drag and drop a message onto a folder to move it. Moves and deletes can be undone.
- Snooze: hide a message until a chosen time, then see all snoozed messages in one list.
- Pagination (up to 300 per page), progressive loading or loading the whole folder. Sort by date, sender, subject or size, and optionally keep flagged messages on top per folder.
- A compact single-line row layout when the message list is wide.
- Safe HTML preview in an isolated frame. Remote images are blocked until you allow them, or loaded only for contacts or trusted senders.
- Attachment preview for images, PDF, text, HTML and video. You can download one attachment or all of them as a ZIP.
- Raw headers, message source, `.eml` download and `.eml` import into any folder.
- One-click unsubscribe from mailing lists when the sender supports it.
- A short context menu with submenus (forward, labels, snooze, filters, sender, more), designed to always fit the window.
- Mailbox quota with warnings at 80% and 95%.
- Several accounts signed in at the same time in one browser, with quick switching.
## Composing
- HTML, plain-text and Markdown editors. The HTML toolbar covers fonts, sizes, colours, lists, quotes, alignment, links, undo and redo.
- Inline images: paste or drag and drop them, then resize, align and crop in place.
- Attachments by drag and drop, with upload progress and a reminder when the text mentions an attachment that isn't there.
- Drafts are saved automatically and can be recovered. Drafts from the Drafts folder, including ones written in other mail clients, open directly for editing.
- Undo Send: a short window to cancel a message after pressing Send.
- Multiple identities, each with Reply-To, automatic Bcc, organisation and text/HTML signatures. Replies pick the matching identity automatically.
- Priority, read-receipt requests and recipient autocomplete from contacts.
- Forward as attachment.
- OpenPGP: key management, signing and encryption (PGP/MIME and inline), decryption and verification, and key discovery.
## Search, labels and contacts
- Full-text search with operators (`from:`, `to:`, `subject:`, `folder:`, `has:attachment`, `is:unread`, `is:flagged`, dates). Matching terms are highlighted, searches can be saved and there is an advanced search dialog.
- Coloured labels with bulk assignment. They can optionally be kept in sync with IMAP keywords, so they are visible in other clients.
- Contacts with photos, several e-mail addresses, phone numbers and postal addresses, plus groups, duplicate detection and merging.
- vCard import and export, including importing a vCard straight from a message.
## Filters (Sieve)
RustBox manages server-side filters over ManageSieve, the standard used by Dovecot Pigeonhole and others.
- **Visual rule editor:** conditions on sender, domain, recipients (To/Cc, To only, Cc only), subject, mailing list, any header, message size, attachments and priority. Conditions can be joined with AND/OR and negated, and a rule can have **exceptions** ("except if…").
- **Actions:** move, copy, move to Trash, add a label, mark as read, flag, redirect (optionally keeping a copy) and discard. A rule can run several actions and stop processing further rules.
- **Templates** for common rules: messages from a sender to a folder, subject words, flagging mail from a VIP, newsletters, mail sent to an alias, large attachments, forwarding a copy.
- **Apply now:** a rule normally affects only new mail. "Check matches" shows how many messages already in a folder match it, and "Apply now" runs its actions on them. Each rule in the list also has its own "Apply now".
- **Always move messages from this sender…** straight from the message context menu, and quick filters created from a message's sender, domain or subject.
- Offers to create a target folder that does not exist yet.
- Every rule is summarised in plain language ("When … Then …") and shown with a live preview of the generated script.
- Out-of-office replies with optional start and end dates, plus a raw script editor with server-side validation, backup and restore.
## Calendar
- Month, week, day and agenda views.
- Events with all-day mode, location, attendees, status, colour and a meeting link.
- Two reminders per event (for example 15 minutes and one day before), with default reminders for new events. Reminders for all-day events fire at the start of the working day.
- ICS import and export, including importing an invitation attachment.
## Notifications and realtime
- New mail shows up immediately thanks to IMAP IDLE and a live connection to the browser.
- Desktop notifications with an optional sound, a choice of folders to watch and Do Not Disturb hours.
- The unread count appears in the browser tab and, where supported, on the app icon.
## Appearance
- Light, dark, system or **time-of-day** theme.
- **43 interface styles**:
- RustBox and classic styles;
- Roundcube Classic, Larry and Elastic;
- styles inspired by popular mail clients and apps;
- editor themes such as Nord, Dracula, Catppuccin, Solarized, Gruvbox and Tokyo Night;
- atmospheric styles;
- retro styles: Windows XP, Mac OS X Aqua, iOS 6, Windows 7, Frutiger Aero and BeOS.
- **Style depth:**
- *colours only*;
- *standard*, which adds the style's layout;
- *immersive*, which also adds the style's shapes, typography, app bar and backdrop.
- An optional **Style gradients** switch.
- A predefined style's layout and typography can be adjusted while it keeps its look. Changing a colour creates a custom copy.
- The RustBox custom style is fully adjustable: colours, fonts, sizes, density, pane widths, corner radius, contrast, selection colour, unread styling, icon size and more. A live warning appears when your custom colours are hard to read.
- An optional colour per account, so it is always clear which account is active.
- Keyboard shortcuts with an in-app reference.
| Gmail | Outlook (immersive) |
|---|---|
|  |  |
| **Dracula (immersive, dark)** | **Windows XP (immersive, gradients)** |
|  |  |
More: [dark theme](screenshots/mail-dark.png) · [Roundcube Elastic](screenshots/style-roundcube-elastic.png)
## Mobile
The interface adapts to phones and tablets: a folder drawer, a full-screen reader and touch-friendly menus.
| Message list | Reader (dark) |
|---|---|
| 
| 
|
## Security and privacy
- Mail server addresses are set by the administrator; users only enter their e-mail address and password.
- Protection against password guessing: per-mailbox and per-address lockouts with growing delays, applied before the mail server is contacted.
- Encrypted, revocable sessions with a list of active sessions and devices.
- Optional strict browser security headers.
- HTML mail is sanitised and shown in an isolated frame. Links open outside the preview, and remote content is blocked by default.
- Secrets are never shown in diagnostics.
## Administration and deployment
- A single executable with the interface built in, a systemd service and Docker Compose examples.
- Databases: SQLite, MySQL/MariaDB or PostgreSQL. Sessions can also be kept in Redis.
- Attachment storage on local disk, a shared filesystem (NFS, CephFS, GlusterFS) or S3-compatible storage.
- Search with a built-in index or OpenSearch. A cluster mode runs several nodes behind a load balancer.
- Health and readiness endpoints, a diagnostics panel for users and an optional, protected diagnostics endpoint for administrators.
- Features can be switched on and off: filters, OpenPGP, multi-account, diagnostics, About page.
- A helper script imports contacts and identities from Roundcube.
See the [README](../README.md) for configuration, [Storage and search](STORAGE_SEARCH_OPERATIONS.md) and [System diagnostics](SYSTEM_DIAGNOSTICS.md).
## Known limitations
- No CalDAV or CardDAV synchronisation yet. Calendar invitations cannot be answered from RustBox, and recurring events are stored but not expanded.
- No password-change integration and no IMAP shared-folder (ACL) management.
- Notifications work while RustBox is open in a browser tab.
- The current status of every area is tracked in [Implementation status](IMPLEMENTATION_STATUS.md).
