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Cocoanetics/SwiftMail

Swift Mail Access to IMAP and SMTP

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) with automatic chunking for large sets
  • Special-use mailbox support
  • Creating new messages via APPEND (draft-friendly)
  • Namespace-aware mailbox resolution (NAMESPACE)
  • Extended search with structured results (ESEARCH)
  • Append size preflight checks (APPENDLIMIT)
  • TLS encryption
  • UID-based operations via UIDPLUS

📊 IMAP Capability Support: Gmail vs iCloud vs Dovecot vs Exchange vs IMAPServer

The table below compares common IMAP capabilities across Gmail, iCloud, Dovecot, Exchange, and SwiftMail's IMAPServer. NIOIMAP indicates capability/command/parser support present in the underlying swift-nio-imap grammar layer. The final column indicates whether IMAPServer implements support for each capability.

| IMAP Capability | Description | Gmail | iCloud | Dovecot | Exchange | NIOIMAP | 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 | ❌ | ✅ | ❌ | ❌ | ❌ | ❌ |

Exchange source (captured 2026-03-05 from outlook.office365.com:993 via IMAPS CAPABILITY):

* CAPABILITY IMAP4 IMAP4rev1 AUTH=PLAIN AUTH=XOAUTH2 SASL-IR UIDPLUS MOVE ID UNSELECT CHILDREN IDLE NAMESPACE LITERAL+

SMTPServer

Handles email sending via SMTP with support for:

  • Multiple authentication methods (PLAIN, LOGIN, XOAUTH2)
  • 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

Creating Drafts via IMAP

SwiftMail lets you build a draft with the shared Email model (also used by SMTP) and store it directly on the server:

let draft = Email(
    sender: EmailAddress(name: "Me", address: "me@example.com"),
    recipients: [],
    subject: "Quarterly update",
    textBody: "Jot down your notes here…"
)

let appendResult = try await imapServer.createDraft(from: draft)
if let uid = appendResult.firstUID {
    print("Draft stored with UID \(uid.value)")
}

Need a custom target mailbox or additional flags? Use the lower-level helper:

try await imapServer.append(
    email: draft,
    to: "Archive/Drafts",
    flags: [.seen]
)

Requirements

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

Dependencies

License

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

Package Metadata

Repository: Cocoanetics/SwiftMail

Stars: 68

Forks: 27

Open issues: 1

Default branch: main

Primary language: swift

License: BSD-2-Clause

README: README.md