Sending Email in Swift: Libraries and Examples for iOS/macOS

Email Sending in Swift (iOS/macOS): Libraries and Practical Examples

Sending emails is one of the key functions of many applications: from user registration and password reset to sending notifications and marketing newsletters. In the Swift ecosystem (iOS/macOS), there are several approaches to implementing this task. In this article, we will review the main libraries, their capabilities, and provide ready-made code examples for integration.

Main Approaches to Sending Email in Swift

There are three main ways to send emails from Swift applications:

• Using MFMailComposeViewController — a built-in system interface for sending emails (iOS only). It allows the user to send an email via the mail client installed on the device, but is not suitable for automatic (server-side) sending.
• Direct SMTP Connection — libraries that implement the SMTP protocol on the client side (e.g., SwiftSMTP). Suitable for sending emails directly from the device without an intermediate server.
• Using Third-Party Service APIs — cloud solutions (Mailgun, SendGrid, Amazon SES) that provide a REST API. This is the most reliable and scalable method for production applications.

SwiftSMTP Library for Direct SMTP Connection

SwiftSMTP is a popular open-source library that implements an SMTP client in Swift. It supports:

• Sending text and HTML emails
• Attachments (images, PDFs, archives)
• TLS/SSL support
• Login/password authentication

Example of sending a simple email via Gmail SMTP:

import SwiftSMTP

let smtp = SMTP(    host: "smtp.gmail.com",     // SMTP server    port: 587,                  // port for TLS    username: "you@gmail.com",    password: "your-app-password")

let mail = Mail(    from: Mail.User(name: "Sender", email: "you@gmail.com"),    to: [Mail.User(name: "Recipient", email: "recipient@example.com")],    subject: "Hello from Swift!",    text: "This is a test email sent using SwiftSMTP.")

smtp.send(mail) { error in    if let error = error {        print("Error sending: \\(error)")    } else {        print("Email sent successfully!")    }}

To work with Gmail, you will need an App Password, as a regular password will not work when two-factor authentication is enabled.

Sending Email via Mailgun (API)

Mailgun is one of the most popular services for sending transactional emails. It provides a simple REST API and an SDK for Swift. Key advantages:

• High deliverability (due to IP reputation)
• Open and click tracking
• Template support

Example of sending an email via the Mailgun API using URLSession:

import Foundation

func sendEmailViaMailgun(to recipient: String, subject: String, body: String) {    let apiKey = "YOUR_MAILGUN_API_KEY"    let domain = "YOUR_DOMAIN.mailgun.org"    let urlString = "https://api.mailgun.net/v3/\\(domain)/messages"        guard let url = URL(string: urlString) else { return }    var request = URLRequest(url: url)    request.httpMethod = "POST"        let credentials = "api:\\(apiKey)"    let authData = credentials.data(using: .utf8)!.base64EncodedString()    request.setValue("Basic \\(authData)", forHTTPHeaderField: "Authorization")    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")        let parameters = [        "from": "My App <noreply@\\(domain)>",        "to": recipient,        "subject": subject,        "text": body    ]        let bodyString = parameters