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Skiff Mail is a privacy-first, end-to-end encrypted email application that empowers free and more effective communication. All messages sent between Skiff Mail users are end-to-end encrypted, and Skiff never stores unencrypted access to messages sent or received from external mail providers.

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Key Features

End-to-End Encryption

All emails between Skiff users are fully encrypted. External emails are encrypted at rest using your private keys.

Rich Text Editor

Compose emails with full text formatting, images, tables, and attachments using Tiptap editor extensions.

Smart Search

Fast, client-side encrypted search across all your emails with instant results.

Advanced Filters

Create custom filters and labels to automatically organize incoming mail.

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Email Composition

Skiff Mail provides a powerful composition experience built on the Tiptap rich text editor.

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Compose Features

  • Rich Text Formatting: Bold, italic, underline, strikethrough, text color, and highlighting
  • Lists and Structure: Bullet lists, numbered lists, blockquotes, and headings
  • Media Support: Inline images, tables with customizable layouts
  • Links: Insert and edit hyperlinks with link tooltips
  • Attachments: Drag and drop file attachments with encryption
  • Scheduled Sending: Schedule emails to be sent at a later time

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Editor Extensions

The mail editor uses several Tiptap extensions: 
// Core extensions
@tiptap/extension-document
@tiptap/extension-paragraph
@tiptap/extension-text
@tiptap/extension-bold
@tiptap/extension-italic
@tiptap/extension-underline
@tiptap/extension-strike
@tiptap/extension-link
@tiptap/extension-image
@tiptap/extension-table
@tiptap/extension-blockquote
@tiptap/extension-code

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Inbox Management

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Thread View

Emails are organized into conversation threads for easier navigation:
  • Automatic thread grouping by subject and participants
  • Expandable/collapsible messages within threads
  • Quick actions: Archive, delete, mark as spam, move to folder
  • Thread-level encryption badge showing security status

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Labels and Folders

Organize your emails with custom labels and system folders:
  • System Folders: Inbox, Sent, Drafts, Trash, Spam, Archive
  • Custom Labels: Create colored labels for categorization
  • Filters: Auto-apply labels based on sender, subject, or content
Mail inbox view

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Encryption Architecture

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End-to-End Encryption

Skiff Mail uses the skiff-mail-protos library to handle encrypted email data structures:
  • Subject Encryption: Email subjects are encrypted using protocol buffers
  • Body Encryption: Both HTML and plain text bodies are separately encrypted
  • Attachment Encryption: Files are encrypted with unique symmetric keys
  • Session Keys: Each email uses encrypted session keys for recipient access

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Encryption Flow

  1. Compose email with plaintext content
  2. Generate symmetric session key for the message
  3. Encrypt message body, subject, and metadata with session key
  4. Encrypt session key with recipient’s public key (for Skiff users)
  5. Store encrypted data on server
  6. Recipients decrypt session key with their private key
  7. Decrypt message content for viewing

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Attachment Handling

Skiff Mail provides secure attachment management:

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Upload and Encryption

  • Drag and drop files directly into compose window
  • Files are encrypted client-side before upload
  • Support for multiple file types and sizes
  • Progress indicators for large uploads

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Download and Decryption

  • Encrypted attachments are downloaded and decrypted locally
  • Preview support for images and PDFs
  • Export attachments to local filesystem
  • Batch download for multiple attachments

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Search Functionality

Skiff Mail implements a privacy-preserving search system:
  • Client-Side Indexing: All search indices are built locally
  • Encrypted Storage: Search indices are encrypted at rest
  • Fast Results: Instant search across thousands of emails
  • Search Filters: Filter by sender, date, has attachments, labels

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Advanced Features

Create powerful automation rules:
  • Filter by sender email address or domain
  • Match subject line patterns
  • Auto-apply labels or move to folders
  • Mark as read/unread automatically
  • Forward or archive based on rules
Filters are stored using the skiff-mail-protos filter protocol buffers.
Migrate your email data:
  • Import: Support for EML format imports
  • Export: Download emails as EML files
  • Bulk Operations: Export multiple threads at once
  • Attachments Included: Exports include all attachments
Create multiple email identities:
  • Generate unique email aliases for different purposes
  • Send from any alias with full encryption
  • Manage alias settings and forwarding rules
  • Quick alias creation from compose window
Use your own domain with Skiff Mail:
  • Configure custom domain DNS settings
  • Send and receive from your domain
  • Full encryption support for custom domains
  • Multiple domains per account (premium)

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Integration Features

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External Email Providers

  • Send and receive emails from Gmail, Outlook, and other providers
  • External emails are encrypted upon receipt
  • SMTP/IMAP compatibility for external accounts
  • Unified inbox for all email accounts

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Calendar Integration

  • Automatically parse calendar invitations
  • Add events directly to Skiff Calendar
  • RSVP to invitations from within email
  • ICS attachment support

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Mobile Support

Skiff Mail is designed for excellent mobile experience:
  • Responsive design for all screen sizes
  • Touch-optimized gestures (swipe to archive/delete)
  • Mobile attachment handling
  • Pull-to-refresh for inbox updates
  • Native mobile apps for iOS and Android

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Privacy and Security

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Zero-Knowledge Architecture

  • Skiff servers never have access to decrypted email content
  • Private keys remain on user devices only
  • Metadata is minimized and encrypted where possible

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Cryptographic Libraries

Skiff Mail leverages several cryptographic libraries:
  • skiff-crypto: Core encryption and decryption functions
  • skiff-crypto-v2: Next-generation crypto primitives
  • @stablelib/chacha20poly1305: Symmetric encryption
  • tweetnacl: Asymmetric key operations

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Technical Implementation

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Source Code Structure

The Skiff Mail application is organized in skemail-web/: 
skemail-web/src/
├── components/
│   ├── Compose/          # Email composition UI
│   ├── MailEditor/       # Tiptap-based editor
│   ├── Thread/           # Thread view and actions
│   ├── mailbox/          # Inbox and folder views
│   ├── Attachments/      # File handling
│   ├── labels/           # Label management
│   └── Settings/         # User preferences
├── apollo/               # GraphQL client configuration
└── cache-worker/         # Offline caching

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GraphQL API

Mail operations use GraphQL mutations and queries:
  • sendMessage: Send encrypted email
  • getThreads: Fetch email threads
  • updateThread: Modify thread properties
  • uploadAttachment: Upload encrypted files
  • createFilter: Create email filter rules
For more details on the GraphQL schema, see the API Reference.

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Getting Started

1

Sign up for Skiff Mail

Create a free account at skiff.com - no personal information required
2

Set up your account

Choose your @skiff.com email address and secure your account with a strong password
3

Import existing emails

Optional: Import your existing emails from other providers using EML export
4

Start sending encrypted emails

Compose your first email - it’s automatically encrypted for Skiff recipients

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