Swift SMTP client

What's New


Swift-SMTP bird

Swift SMTP client.

Build Status macOS Linux Apache 2


  • Connect securely through SSL/TLS when needed
  • Authenticate with CRAM-MD5, LOGIN, PLAIN, or XOAUTH2
  • Send emails with local file, HTML, and raw data attachments
  • Add custom headers
  • Documentation

Swift Version

macOS & Linux: Swift 5.2 or above.


You can add SwiftSMTP to your project using Swift Package Manager. If your project does not have a Package.swift file, create one by running swift package init in the root directory of your project. Then open Package.swift and add SwiftSMTP as a dependency. Be sure to add it to your desired targets as well:

// swift-tools-version:4.0

import PackageDescription

let package = Package(
    name: "MyProject",
    products: [
            name: "MyProject",
            targets: ["MyProject"]),
    dependencies: [
        .package(url: "https://github.com/Kitura/Swift-SMTP", .upToNextMinor(from: "5.1.0")),    // add the dependency
    targets: [
            name: "MyProject",
            dependencies: ["SwiftSMTP"]),                                                           // add targets
        .testTarget(                                                                                // note "SwiftSMTP" (NO HYPHEN)
            name: "MyProjectTests",
            dependencies: ["MyProject"]),

After adding the dependency and saving, run swift package generate-xcodeproj in the root directory of your project. This will fetch dependencies and create an Xcode project which you can open and begin editing.

Migration Guide

Version 5.0.0 brings breaking changes. See the quick migration guide here.


Initialize an SMTP instance:

import SwiftSMTP

let smtp = SMTP(
    hostname: "smtp.gmail.com",     // SMTP server address
    email: "user@gmail.com",        // username to login
    password: "password"            // password to login


Additional parameters of SMTP struct:

public init(hostname: String,
            email: String,
            password: String,
            port: Int32 = 587,
            tlsMode: TLSMode = .requireSTARTTLS,
            tlsConfiguration: TLSConfiguration? = nil,
            authMethods: [AuthMethod] = [],
            domainName: String = "localhost",
            timeout: UInt = 10)

By default, the SMTP struct connects on port 587 and sends mail only if a TLS connection can be established. It also uses a TLSConfiguration that uses no backing certificates. View the docs for more configuration options.

Send email

Create a Mail object and use your SMTP handle to send it. To set the sender and receiver of an email, use the User struct:

let drLight = Mail.User(name: "Dr. Light", email: "drlight@gmail.com")
let megaman = Mail.User(name: "Megaman", email: "megaman@gmail.com")

let mail = Mail(
    from: drLight,
    to: [megaman],
    subject: "Humans and robots living together in harmony and equality.",
    text: "That was my ultimate wish."

smtp.send(mail) { (error) in
    if let error = error {

Add Cc and Bcc:

let roll = Mail.User(name: "Roll", email: "roll@gmail.com")
let zero = Mail.User(name: "Zero", email: "zero@gmail.com")

let mail = Mail(
    from: drLight,
    to: [megaman],
    cc: [roll],
    bcc: [zero],
    subject: "Robots should be used for the betterment of mankind.",
    text: "Any other use would be...unethical."


Send attachments

Create an Attachment, attach it to your Mail, and send it through the SMTP handle. Here's an example of how you can send the three supported types of attachments--a local file, HTML, and raw data:

// Create a file `Attachment`
let fileAttachment = Attachment(
    filePath: "~/img.png",          
    // "CONTENT-ID" lets you reference this in another attachment
    additionalHeaders: ["CONTENT-ID": "img001"]

// Create an HTML `Attachment`
let htmlAttachment = Attachment(
    htmlContent: "<html>Here's an image: <img src=\"cid:img001\"/></html>",
    // To reference `fileAttachment`
    related: [fileAttachment]

// Create a data `Attachment`
let data = "{\"key\": \"hello world\"}".data(using: .utf8)!
let dataAttachment = Attachment(
    data: data,
    mime: "application/json",
    name: "file.json",
    // send as a standalone attachment
    inline: false   

// Create a `Mail` and include the `Attachment`s
let mail = Mail(
    from: from,
    to: [to],
    subject: "Check out this image and JSON file!",
    // The attachments we created earlier
    attachments: [htmlAttachment, dataAttachment]

// Send the mail

/* Each type of attachment has additional parameters for further customization */

Send multiple mails

let mail1: Mail = //...
let mail2: Mail = //...

smtp.send([mail1, mail2],
    // This optional callback gets called after each `Mail` is sent.
    // `mail` is the attempted `Mail`, `error` is the error if one occured.
    progress: { (mail, error) in

    // This optional callback gets called after all the mails have been sent.
    // `sent` is an array of the successfully sent `Mail`s.
    // `failed` is an array of (Mail, Error)--the failed `Mail`s and their corresponding errors.
    completion: { (sent, failed) in


Inspired by Hedwig and Perfect-SMTP.


Apache v2.0


  • Swift Tools 5.0.0
View More Packages from this Author


Last updated: Sat Sep 30 2023 00:46:26 GMT-0900 (Hawaii-Aleutian Daylight Time)