SwiftMail

A Swift package for comprehensive email functionality, providing robust IMAP and SMTP client implementations.

Overview

SwiftMail is a powerful email package that enables you to work with email protocols in your Swift applications. The package provides two main components:

IMAPServer

Handles IMAP server connections for retrieving and managing emails. Implements key IMAP capabilities including:

• Mailbox operations (SELECT, LIST, COPY, MOVE)
• Message operations (FETCH headers/parts/structure, STORE flags)
• Special-use mailbox support
• TLS encryption
• UID-based operations via UIDPLUS

📊 IMAP Capability Support: Gmail vs iCloud vs IMAPServer

The table below compares common IMAP capabilities across Gmail, iCloud, and SwiftMail's IMAPServer. The final column indicates whether IMAPServer implements support for each capability.

IMAP Capability	Description	Gmail	iCloud	IMAPServer
IMAP4rev1	Standard IMAP protocol (RFC 3501)	✅	✅	✅
UNSELECT	Unselect mailbox without selecting another (RFC 3691)	✅	✅	✅
IDLE	Push new message alerts (RFC 2177)	✅	✅	✅
NAMESPACE	Query folder structure roots (RFC 2342)	✅	✅	❌
QUOTA	Storage quota reporting (RFC 2087)	✅	✅	✅
ID	Identify client/server (RFC 2971)	✅	✅	✅
XLIST	Gmail folder role mapping (legacy)	✅	❌	❌
CHILDREN	Show folder substructure (RFC 3348)	✅	❌	❌
X-GM-EXT-1	Gmail labels, threads, msg IDs	✅	❌	❌
UIDPLUS	Enhanced UID operations (RFC 4315)	✅	✅	✅
COMPRESS=DEFLATE	zlib compression (RFC 4978)	✅	❌	❌
ENABLE	Enable optional extensions (RFC 5161)	✅	✅	❌
MOVE	Native IMAP MOVE command (RFC 6851)	✅	❌	✅
CONDSTORE	Efficient state sync (RFC 7162)	✅	✅	❌
ESEARCH	Extended search (RFC 4731)	✅	✅	❌
UTF8=ACCEPT	UTF-8 folder & header support (RFC 6855)	✅	❌	❌
LIST-EXTENDED	Advanced mailbox listing (RFC 5258)	✅	❌	❌
LIST-STATUS	List + status in one (RFC 5819)	✅	✅	❌
LITERAL-	Literal string optimization (RFC 7888)	✅	❌	❌
SPECIAL-USE	Modern folder role marking (RFC 6154)	✅	❌	✅
APPENDLIMIT=…	Message size limit for uploads	✅	❌	❌
QRESYNC	Quick resync (RFC 5162)	❌	✅	❌
SORT	Server-side message sorting (RFC 5256)	❌	✅	❌
ESORT	Extended SORT results (RFC 5267)	❌	✅	❌
CONTEXT=SORT	Persistent sort context	❌	✅	❌
WITHIN	Search by relative time (RFC 5032)	❌	✅	❌
SASL-IR	Initial SASL response support (RFC 4959)	❌	✅	❌
XAPPLEPUSHSERVICE	Apple push integration for Mail app	❌	✅	❌
XAPPLELITERAL	Apple literal transmission optimization	❌	✅	❌
X-APPLE-REMOTE-LINKS	Apple-specific remote links extension	❌	✅	❌

SMTPServer

Handles email sending via SMTP with support for:

• Multiple authentication methods (PLAIN, LOGIN)
• TLS encryption
• 8BITMIME support
• Full MIME email composition
• Multiple recipients (To, CC, BCC)

Command Line Demos

The package includes command line demos that showcase the functionality of both the IMAP and SMTP libraries:

• SwiftIMAPCLI: Demonstrates IMAP operations like listing mailboxes and fetching messages
• SwiftSMTPCLI: Demonstrates sending emails via SMTP

Both demos look for a .env file in the current working directory for configuration. Create a .env file with the following variables:

# IMAP Configuration
IMAP_HOST=imap.example.com
IMAP_PORT=993
IMAP_USERNAME=your_username
IMAP_PASSWORD=your_password

# SMTP Configuration
SMTP_HOST=smtp.example.com
SMTP_PORT=587
SMTP_USERNAME=your_username
SMTP_PASSWORD=your_password

Note for Gmail Users: When using Gmail, you cannot authenticate with your Google account password. Instead, you must create an app-specific password and use that as your password in the configuration above.

To run the demos:

# Run the IMAP demo
swift run SwiftIMAPCLI

# Run the SMTP demo
swift run SwiftSMTPCLI

# Run with debug logging enabled (recommended for development)
ENABLE_DEBUG_OUTPUT=1 OS_ACTIVITY_DT_MODE=debug swift run SwiftIMAPCLI
ENABLE_DEBUG_OUTPUT=1 OS_ACTIVITY_DT_MODE=debug swift run SwiftSMTPCLI

The debug logging options:

• ENABLE_DEBUG_OUTPUT=1: Enables trace level logging
• OS_ACTIVITY_DT_MODE=debug: Formats debug output in a readable way

Requirements

• Swift 5.9+
• macOS 11.0+
• iOS 14.0+
• tvOS 14.0+
• watchOS 7.0+
• macCatalyst 14.0+

Dependencies

• SwiftNIO
• SwiftNIOSSL
• SwiftNIOIMAP (for IMAP only)
• SwiftDotenv (for CLI demos)
• Swift Testing (for tests only)
• Swift Logging

License

This project is licensed under the BSD 2-Clause License - see the LICENSE file for details.