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How to Send Emails Using an API

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Author: Alex Grosu
Alex Grosu
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Key Takeaways

This post will provide a complete walkthrough for integrating an email API focused specifically on sending emails. It will cover the setup, implementation across different programming languages, and best practices to ensure reliable delivery and smooth integration. You’ll find:

  • Code samples and implementation guides for sending emails through the Nylas API across various programming environments, including Ruby, Python, and Node.
  • Step-by-step examples for languages without dedicated SDKs, like PHP, Rust, Node-Red and C#, showing how to set up and send emails directly with API requests.
  • Advanced Features: Techniques for adding attachments, personalizing content, and tracking email engagement.
  • Best practices for deliverability and error handling, ensuring your emails reach the inbox reliably and your API integration is robust.

Whether you’re setting up basic email notifications or high-volume automated messaging, this post will walk you through every step, from setup to sending, ensuring your application delivers emails effectively with minimal complexity.

In today’s digital world, sending emails programmatically has become essential for applications handling user notifications, transactional messages, and automated communication. Using an Email API is the most efficient way to send emails directly from your application without managing the complexities of email servers or manual configuration.

What is an Email API for Sending Emails?

An email API provides a streamlined, programmable interface that connects your application to email service providers like Gmail, Outlook, and others. With a few API calls, developers can send customized emails on behalf of users without ever needing to open an inbox. This process is ideal for applications that rely on automated email sending for everything from account notifications to marketing messages.

Why Use an Email API for Sending Emails?

Leveraging an email API to send emails provides significant advantages for developers and users alike:

  • For Developers: Email APIs handle the technical aspects of email delivery, including authentication, deliverability, and scalability. This means that instead of setting up servers or managing protocols, developers can quickly integrate email functions, saving time and reducing development complexity.
  • For Users: APIs ensure reliable, timely delivery of emails, providing users with instant updates, notifications, and relevant information without delay. By automating email processes, users receive a seamless, uninterrupted experience with the application.

Benefits of Using an Email API for Sending Emails

Integrating an email API specifically for sending emails can provide substantial value to both development teams and end-users, making it a preferred choice for many applications. Here’s why:

Advantages for Development Teams

  • Simplified Integration and Management
    An email API abstracts away the complex email protocols (like SMTP) and server configurations needed to send emails. With just a few API calls, developers can integrate email-sending functionality quickly and avoid the technical challenges of traditional email setups.
  • Efficiency in Time and Resources
    By outsourcing the technical handling of email to a reliable API, developers save time and resources that would otherwise be spent on maintaining infrastructure and ensuring deliverability. This frees up engineering time for core features and faster product releases.
  • Scalability for High-Volume Sending
    As an application grows, so does its need for scalable, high-volume email sending. Email APIs are built to handle this demand, supporting hundreds, thousands, or even millions of emails per day without requiring additional setup.
  • Enhanced Deliverability
    Reputable email APIs are optimized for high deliverability, helping emails avoid spam filters and reach inboxes reliably. APIs often manage IP reputation, provide tools to follow sending best practices, and reduce the risk of emails ending up in spam.

Benefits for End Users

  • Timely and Reliable Communication
    Users expect timely responses and updates from applications they interact with. Using an email API ensures important messages—like password resets, account notifications, or confirmations—are sent immediately, improving user satisfaction and trust.
  • Personalized Messaging
    Email APIs often support dynamic content, which means you can easily personalize emails to each user’s context and behavior. Personalized emails are more engaging, helping users feel more connected to the application.
  • Seamless User Experience
    Automating email communications through an API provides a smooth, professional experience for users. Instead of manual messaging delays, users receive consistent, automated updates that align with their actions within the app, reducing friction and enhancing engagement.

Key Use Cases for Sending Emails with an API

  • Transactional Emails: Automated messages like account activations, order confirmations, or password resets triggered by user actions.
  • Notifications and Alerts: Real-time updates about account activity, system changes, or reminders that keep users informed.
  • Marketing and Engagement: Newsletters, promotions, or personalized product recommendations sent to users based on their preferences.

Using an email API for sending emails optimizes the communication process, making it reliable, scalable, and tailored to user needs. In the next sections, we’ll explore how to set up and use an email API for different programming environments and scenarios, helping you implement these benefits directly into your application.

How to Get Started with an Email API

Setting up an email API for sending emails involves a few essential steps to ensure seamless integration and secure functionality. Here’s how to get started:

Step 1: Select an Email API Provider

Begin by choosing an email API provider that matches your application’s needs. Consider the following factors:

  • Feature Set: Look for capabilities like high deliverability, tracking, personalization, and attachment support.
  • Scalability: Ensure the provider can handle your current and anticipated email volume.
  • Documentation and Support: Good documentation and responsive support make integration faster and easier.
  • Pricing: Review the pricing structure, especially if you plan to send high volumes of emails.

For this blog post, we’ll be using Nylas as the email API product. Nylas is a popular choice for sending and managing emails because it offers:

Step 2: Sign Up and Obtain API Credentials

After selecting a provider, create an account and obtain the necessary API credentials, typically including:

  • API Key or Client ID and Secret: These are used to authenticate your application with the email API.
  • Access Token: Some APIs require an access token specific to each user or sender account.

For security, store these credentials in environment variables rather than hardcoding them into your application. This minimizes the risk of exposing sensitive information in code repositories.

Let’s do that with Nylas. To start:

  1. Create a Nylas Account: Go to Nylas and sign up for a developer account.
  2. Register Your Application: Once signed in, create a new application on the Nylas dashboard. This application will provide you with:
    • CLIENT_ID and API_KEY: These are unique identifiers for your application.

Store Credentials Securely: Save these credentials in environment variables. For example, in a .env file:

NYLAS_API_KEY=your_api_key

NYLAS_API_URI=your_api_uri

NYLAS_GRANT_ID=your_grant_id
  1. This approach keeps sensitive information secure and prevents accidental exposure in code repositories.

Step 3: Set Up Your Development Environment

Before you start coding, prepare your environment for a smooth integration:

  • Install Required SDKs or Libraries: If the provider offers SDKs (e.g., for Ruby, Python, or Node), install them to streamline API calls. For languages without SDKs, set up libraries to handle HTTP requests.
  • Configure Environment Variables: Store API credentials in environment variables to keep your code secure and easily adaptable across different environments (development, staging, production).
  • Enable Necessary Permissions: Some email APIs may require permissions to access user data or email sending functionality. Check the provider’s settings to ensure all required permissions are granted.

Now we’ll prepare our development environment to start using the Nylas API:

  1. Install the Nylas SDK: If you’re using a language that Nylas supports with an SDK (such as Ruby, Python, or Node.js), install the SDK.

Node.js

Ruby

Python

Java

npm install nylas
gem install nylas

pip install nylas
//for Java/Kotlin, use inside your pom.xml

<groupId>com.nylas.sdk</groupId>
<artifactId>nylas</artifactId>
<version>2.5.1</version>
See the docs

Suppose you’re using a language without a dedicated SDK (such as PHP, Rust or C#). In that case, you can use standard HTTP request libraries like axios (JavaScript), reqwest (Rust), or RestSharp (C#) to interact with the API.

2. Set Up Environment Variables: Store your API credentials in environment variables to ensure secure and efficient management across development, staging, and production environments.

3. Enable Necessary Permissions: In your Nylas application settings, ensure you’ve enabled the required permissions for sending emails. Nylas allows you to specify access levels based on your application’s needs.

Step 4: Make Your First API Call to Send an Email

With the API credentials set up, you’re ready to send a test email:

  • Compose Your Email: Using the API documentation, set up the email parameters such as the recipient’s email address, subject line, and message content.
  • Execute the API Call: Send the email using the appropriate endpoint. Most APIs allow you to specify options for plain text, HTML content, and attachments.
  • Handle Responses: Monitor the API’s response to confirm that the email was sent successfully or to catch any errors. Logging these responses can help with troubleshooting.

Now that we have the environment is set up, we’re ready to send an email through Nylas:

  1. Compose the Email: Define the recipient’s email address, subject, and message body. Here’s an example in cURL:

Curl

curl -X POST "https://api.us.nylas.com/v3/grants/NYLAS_GRANT_ID/messages/send" \
 -H "accept: application/json"\
 -H "content-type: application/json" \
 -H "authorization: Bearer NYLAS_API_KEY"\
 -d '{"subject":"Hello",
      "body":"Hello from Nylas",
      "to":[{"name":"Swag","email":"[email protected]"}]
     }'
See the docs

2. Execute the API Call: Run this on your terminal window.
3. Handle Responses: Monitor the response from Nylas. A successful response indicates the email was sent, while an error response will provide details if something went wrong. Logging these responses is helpful for troubleshooting and verifying that emails are being delivered as expected.

By completing these steps, you’ll have a working setup to send emails through an API. In the following sections, we’ll provide examples for sending emails using various SDKs and languages, helping you build a reliable and efficient email-sending feature into your application.

Sending Emails with Different SDKs and Platforms

Integrating an email API to send emails is straightforward, especially when using SDKs that handle much of the setup and configuration. Below, we cover how to send emails with Nylas using different SDKs and programming environments, including Ruby, Python, Node, and options for other languages.

a. Install the Nylas SDK in your Ruby, Python, Java, Kotlin or Node environments.

Node.js

Ruby

Python

Java

npm install nylas
npm install dotenv
gem install nylas
gem install dotenv
pip install nylas
pip install python-dotenv
<dependency>
   <groupId>com.nylas.sdk</groupId>
   <artifactId>nylas</artifactId>
   <version>2.5.1</version>
 </dependency>
 <dependency>
   <groupId>io.github.cdimascio</groupId>
   <artifactId>dotenv-kotlin</artifactId>
   <version>6.4.2</version>
 </dependency>
See the docs

b. Setup and Sending an Email: Configure your credentials and create a draft email with

Node.js

Ruby

Python

Java

import 'dotenv/config'
import Nylas from 'nylas'
import * as readline from "readline";

const NylasConfig = {
 apiKey: process.env.NYLAS_API_KEY,
 apiUri: process.env.NYLAS_API_URI,
}

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

const askQuestion = (question) => {
  return new Promise((resolve) => {
    rl.question(question, (answer) => {
      resolve(answer);
    });
  });
};

const nylas = new Nylas(NylasConfig)

const main = async () => {
  const subject = await askQuestion('Enter a subject: ');
  const body = await askQuestion('Enter the body: ');
  const name = await askQuestion('Enter the recipient\'s name: ');
  const email = await askQuestion('Enter the recipient\'s email: ');

  try {
    const result = await nylas.messages.send({
      identifier: process.env.NYLAS_GRANT_ID,
      requestBody: {
        subject: subject,
        body: body,
        to: [{ name: name, email: email }],
      },
    });
  
    console.log('Result:', result)
  } catch (error) {
    console.error('Error sending email:', error)
  }

  rl.close();
};

main();

//Run it with node sendEmail.js
require 'dotenv/load'
require 'nylas'	
require 'json'

nylas = Nylas::Client.new(
	api_key: ENV["NYLAS_API_KEY"],
	api_uri: ENV["NYLAS_API_URI"]
)

print "Enter a subject: "
subject = gets.chomp
print "Enter the body: "
body = gets.chomp
print "Enter the recipient\'s name: "
name = gets.chomp
print "Enter the recipient\'s email: "
email = gets.chomp

request_body = {
    subject: subject,
    body: body,
    to: [{name: name, email: email}]
}

email, _ = nylas.messages.send(identifier: ENV["NYLAS_GRANT_ID"], 
           request_body: request_body)
puts JSON.pretty_generate(email)

#Run it with ruby sendEmail.rb
from nylas import Client
from dotenv import load_dotenv
import os

load_dotenv()

nylas = Client(
    api_key = os.environ.get("NYLAS_API_KEY")
)

subject = input("Enter a subject: ")
body = input("Enter the subject: ")
name = input("Enter the recipient\'s name: ")
email = input("Enter the recipient\'s email: ")

body = {"subject" : subject, 
             "body": body,
             "to":[{"name": name,
             "email": email}]}

message = nylas.messages.send(os.environ.get("NYLAS_GRANT_ID"), 
                              request_body = body).data
print(message)

#Run it with python3 sendEmail.py
import com.nylas.NylasClient;
import com.nylas.models.*;
import io.github.cdimascio.dotenv.Dotenv;
import java.io.Console;
import java.util.ArrayList;
import java.util.List;

public class sendEmail {
    public static void main(String[] args) throws NylasSdkTimeoutError, NylasApiError {
        Dotenv dotenv = Dotenv.load();
        NylasClient nylas = new NylasClient.Builder(dotenv.get("NYLAS_API_KEY"))
                                           .apiUri(dotenv.get("NYLAS_API_URI")).build();

        Console console = System.console();
        System.out.print("Enter a subject: ");
        String subject = console.readLine();
        System.out.print("Enter the body: ");
        String body = console.readLine();
        System.out.print("Enter the recipient's name: ");
        String name = console.readLine();
        System.out.print("Enter the recipient's email: ");
        String email = console.readLine();

        List<EmailName> emailNames = new ArrayList<>();
        emailNames.add(new EmailName(email, name));

        SendMessageRequest requestBody = new SendMessageRequest.Builder(emailNames).
                subject(subject).
                body(body).
                build();

        Response<Message> response = nylas.messages().
                                     send(dotenv.get("NYLAS_GRANT_ID"), requestBody);
        System.out.println(response.getData());
    }
}

//Run it with mvn exec:java -Dexec.mainClass=”sendEmail” -Dexec.cleanupDaemonThreads=false
See the docs

Advanced Email Sending Features

When using an email API to send emails, there are several advanced features that can enhance functionality, improve engagement, and provide valuable insights. Here are some powerful options to consider:

1. Adding Attachments to Emails

Many applications require sending files alongside emails, such as invoices, reports, or media files. Email APIs often support attachments, allowing you to include these directly in your messages:

  • File Size and Format Limitations: Be aware of the API’s limitations on file sizes and supported formats.

Adding Attachments: Most APIs allow you to attach files by specifying the file path or by encoding the file in Base64 format, depending on the language and SDK used. 

Attachments add depth to your emails, allowing for better communication through supporting documents or multimedia.

Node.js

Ruby

Python

Java

import 'dotenv/config'
import Nylas from 'nylas'
import fs from 'fs';
import path from 'path';
const NylasConfig = {
 apiKey: process.env.NYLAS_API_KEY,
 apiUri: process.env.NYLAS_API_URI,
}

const nylas = new Nylas(NylasConfig)

const main = async () => {

  try {
	  
    const attachmentPath = path.resolve('nylas_logo.png');
	const fileContent = fs.readFileSync(attachmentPath);
	  
    const result = await nylas.messages.send({
      identifier: process.env.NYLAS_GRANT_ID,
      requestBody: {
        subject: "Here's your file",
        body: "Please see the attached file",
        to: [{ name: "Swag", email: "[email protected]" }],
         attachments: [{
            content: fileContent.toString('base64'),
            contentType: "image/png",
            filename: 'nylas_logo.png'
          }]
      },
    });
  
    console.log('Result:', result)
  } catch (error) {
    console.error('Error sending email:', error)
  }
};

main();
require 'dotenv/load'
require 'nylas'	
require 'json'

nylas = Nylas::Client.new(
	api_key: ENV["NYLAS_API_KEY"],
	api_uri: ENV["NYLAS_API_URI"]
)

file = Nylas::FileUtils.attach_file_request_builder("nylas_logo.png")

request_body = {
    subject: "Here's your file",
    body: "Please see the attached file",
    to: [{name: "Swag", email: "[email protected]"}],
    attachments: [file]
}

email, _ = nylas.messages.send(identifier: ENV["NYLAS_GRANT_ID"], 
           request_body: request_body)
puts JSON.pretty_generate(email)


from nylas import Client
from dotenv import load_dotenv
import os
from nylas import utils

load_dotenv()

nylas = Client(
    api_key = os.environ.get("NYLAS_API_KEY")
)

attachment = utils.file_utils.attach_file_request_builder("nylas_logo.png")

body = {"subject" : "Here's your file", 
             "body": "Please see the attached file",
             "to":[{"name": "Swag",
             "email": "[email protected]"}],
             "attachments": [attachment]}

message = nylas.messages.send(os.environ.get("NYLAS_GRANT_ID"), 
                              request_body = body).data
print(message)


import com.nylas.NylasClient;
import com.nylas.models.*;
import io.github.cdimascio.dotenv.Dotenv;
import com.nylas.util.FileUtils;
import java.util.ArrayList;
import java.util.List;

public class sendEmailAttachment {
    public static void main(String[] args) throws NylasSdkTimeoutError, NylasApiError {
        Dotenv dotenv = Dotenv.load();
        NylasClient nylas = new NylasClient.Builder(dotenv.get("NYLAS_API_KEY"))
                                           .apiUri(dotenv.get("NYLAS_API_URI")).build();

        CreateAttachmentRequest attachment =
                FileUtils.attachFileRequestBuilder("src/main/java/nylas_logo.png");
        List<CreateAttachmentRequest> request = new ArrayList<>();
        request.add(attachment);

        List<EmailName> emailNames = new ArrayList<>();
        emailNames.add(new EmailName("[email protected]", "Swag"));

        SendMessageRequest requestBody = 
                new SendMessageRequest.Builder(emailNames).
                subject("Here's your file").
                body("Please see the attached file").
                attachments(request).
                build();

        Response<Message> response = nylas.messages().
                                     send(dotenv.get("NYLAS_GRANT_ID"), requestBody);
        System.out.println(response.getData());
    }
}
See the docs

2. Personalizing Emails with Dynamic Content

Personalization boosts user engagement by tailoring the content to individual recipients. Email APIs make it easy to add dynamic fields that adjust based on user data:

  • Basic Personalization: Add placeholders for user-specific details like name, location, or recent activity. For example, Hello {{name}} could be dynamically replaced based on user data.
  • Advanced Personalization: Tailor content sections based on user preferences or behaviors, such as recent purchases or service usage.

Dynamic, personalized emails create a more meaningful connection with recipients, improving open and click-through rates.

3. Using HTML and Plain Text Versions

To ensure that emails display correctly across all devices and email clients, it’s recommended to include both HTML and plain text versions of your emails:

  • HTML Version: Use HTML to format your email with styles, images, and links, giving it a visually appealing layout.
  • Plain Text Version: Include a plain text alternative to ensure that users who prefer simpler formats or have HTML disabled can still read your message.

Including both formats ensures that your emails are accessible and that they comply with email best practices, which can improve deliverability.

4. Tracking and Analytics for Engagement Insights

Tracking opens, clicks, and other metrics allows you to gauge the effectiveness of your emails and gain insights into user engagement:

  • Open Tracking: Most email APIs offer open tracking, which uses a small tracking pixel to detect when an email is opened. This can help you understand the reach and visibility of your messages.
  • Click Tracking: Track clicks on links within your emails to measure engagement with specific content or calls-to-action.
  • Reply Tracking: Some APIs support reply tracking, which notifies you if a user responds to your email. This can be useful for customer support or sales workflows.

Node.js

Ruby

Python

Java

import 'dotenv/config'
import Nylas from 'nylas'
const NylasConfig = {
 apiKey: process.env.NYLAS_API_KEY,
 apiUri: process.env.NYLAS_API_URI,
}

const nylas = new Nylas(NylasConfig)

const main = async () => {

  try {
	  	  
    const result = await nylas.messages.send({
      identifier: process.env.NYLAS_GRANT_ID,
      requestBody: {
        subject: "Engagement Email",
        body: "Click the <a href='https://nylas.com'>link</a> to learn more!",
        to: [{ name: "Swag", email: "[email protected]" }],
        tracking_options: {label: "My first tracking", 
                       opens: true, links: true}
      },
    });
  
    console.log('Result:', result)
  } catch (error) {
    console.error('Error sending email:', error)
  }
};

main();
require 'dotenv/load'
require 'nylas'	
require 'json'

nylas = Nylas::Client.new(
	api_key: ENV["NYLAS_API_KEY"],
	api_uri: ENV["NYLAS_API_URI"]
)

request_body = {
    subject: "Engagement Email",
    body: "Click the <a href='https://nylas.com'>link</a> to learn more!",
    to: [{name: "Swag", email: "[email protected]"}],
    tracking_options: {label: "My first tracking", opens: true, links: true}
}

email, _ = nylas.messages.send(identifier: ENV["NYLAS_GRANT_ID"], 
           request_body: request_body)
puts JSON.pretty_generate(email)
from nylas import Client
from dotenv import load_dotenv
import os

load_dotenv()

nylas = Client(
    api_key = os.environ.get("NYLAS_API_KEY")
)

body = {"subject" : "Engagement Email", 
             "body": "Click the <a href='https://nylas.com'>link</a> to learn more!",
             "to":[{"name": "Swag",
             "email": "[email protected]"}],
             "tracking_options": {"label": "My first tracking", 
                       "opens": True, "links": True}}

message = nylas.messages.send(os.environ.get("NYLAS_GRANT_ID"), 
                              request_body = body).data
print(message)
import com.nylas.NylasClient;
import com.nylas.models.*;
import io.github.cdimascio.dotenv.Dotenv;
import java.util.ArrayList;
import java.util.List;

public class sendEmailTracking {
    public static void main(String[] args) throws NylasSdkTimeoutError, NylasApiError {
        Dotenv dotenv = Dotenv.load();
        NylasClient nylas = new NylasClient.Builder(dotenv.get("NYLAS_API_KEY"))
                                           .apiUri(dotenv.get("NYLAS_API_URI")).build();

        List<EmailName> emailNames = new ArrayList<>();
        emailNames.add(new EmailName("[email protected]", "Swag"));

        TrackingOptions trackingOptions =
                new TrackingOptions("My first tracking", true, true, null);

        SendMessageRequest requestBody = new SendMessageRequest.Builder(emailNames).
                subject("Engagement Email").
                body("Click the <a href='https://nylas.com'>link</a> to learn more!").
                trackingOptions(trackingOptions).
                build();

        Response<Message> response = nylas.messages().
                                     send(dotenv.get("NYLAS_GRANT_ID"), requestBody);
        System.out.println(response.getData());
    }
}
See the docs

Tracking provides valuable data, enabling you to adjust and optimize email content over time based on actual user interactions.

In order to monitor tracking, we need to utilize Notifications with their corresponding Notification schemas.

5. Scheduling Email Delivery

Scheduling email sends for a specific time or date can be essential for timing-sensitive content, such as newsletters or promotional campaigns:

  • Delay or Schedule Emails: Some APIs allow you to set a future date and time for email delivery, ensuring your message reaches users at the optimal moment.
  • Timezone Considerations: If your audience is spread across different time zones, segment users and schedule emails according to their local time to improve open rates.

This feature is particularly useful for marketing, ensuring that users receive content when they’re most likely to engage.

Incorporating these advanced features into your email-sending process enhances the effectiveness of your messages, improves engagement, and offers deeper insights into user behavior. By using attachments, personalization, tracking, and scheduling, you can create a more impactful and data-driven email strategy.

Node.js

Ruby

Python

Java

import 'dotenv/config'
import Nylas from 'nylas'
import date from 'date-and-time';
const NylasConfig = {
 apiKey: process.env.NYLAS_API_KEY,
 apiUri: process.env.NYLAS_API_URI,
}

const nylas = new Nylas(NylasConfig)

const now = new Date(); 
const scheduled = date.addMinutes(now,2); 

const main = async () => {

  try {
    const result = await nylas.messages.send({
      identifier: process.env.NYLAS_GRANT_ID,
      requestBody: {
        subject: "This is a scheduled message",
        body: "I sent this email 2 minutes ago",
        to: [{ name: "Blag", email: "[email protected]" }],
        send_at: (scheduled.getTime() - scheduled.getMilliseconds()) / 1000,
      },
    });
  
    console.log('Result:', result)
  } catch (error) {
    console.error('Error sending email:', error)
  }
};

main();
require 'dotenv/load'
require 'nylas'	
require 'json'

nylas = Nylas::Client.new(
	api_key: ENV["NYLAS_API_KEY"],
	api_uri: ENV["NYLAS_API_URI"]
)

class Numeric
  def minutes; self/1440.0 end
  alias :minute :minutes

  def seconds; self/86400.0 end
  alias :second :seconds
end

d = DateTime.now
d = d + 2.minute
scheduled =  DateTime.parse(d.to_s).strftime("%s").to_i

request_body = {
    subject: "This is a scheduled message",
    body: "I sent this email 2 minutes ago",
    to: [{name: "Swag", email: "[email protected]"}],
    send_at: scheduled
}

email, _ = nylas.messages.send(identifier: ENV["NYLAS_GRANT_ID"], 
           request_body: request_body)
puts JSON.pretty_generate(email)
from nylas import Client
from dotenv import load_dotenv
import os
import pendulum

load_dotenv()

nylas = Client(
    api_key = os.environ.get("NYLAS_API_KEY")
)

now = pendulum.now()
now = now.add(minutes=2)

body = {"subject" : "This is a scheduled message", 
             "body": "I sent this email 2 minutes ago",
             "to":[{"name": "Swag",
             "email": "[email protected]"}],
             "send_at": now.int_timestamp
}

message = nylas.messages.send(os.environ.get("NYLAS_GRANT_ID"), 
                              request_body = body).data
print(message)


import com.nylas.NylasClient;
import com.nylas.models.*;
import io.github.cdimascio.dotenv.Dotenv;
import java.util.ArrayList;
import java.util.List;
import java.util.Calendar;

public class sendEmailScheduled {
    public static void main(String[] args) throws NylasSdkTimeoutError, NylasApiError {
        Dotenv dotenv = Dotenv.load();
        NylasClient nylas = new NylasClient.Builder(dotenv.get("NYLAS_API_KEY"))
                                           .apiUri(dotenv.get("NYLAS_API_URI")).build();

        List<EmailName> emailNames = new ArrayList<>();
        emailNames.add(new EmailName("[email protected]", "Swag"));

        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.MINUTE, 2);

        SendMessageRequest requestBody = new SendMessageRequest.Builder(emailNames).
                subject("This is a scheduled message").
                body("I sent this email 2 minutes ago").
                sendAt((int) (calendar.toInstant().getEpochSecond())).
                build();

        Response<Message> response = nylas.messages().
                                     send(dotenv.get("NYLAS_GRANT_ID"), requestBody);
        System.out.println(response.getData());
    }
}
See the docs

Best Practices for Email API Integration

To ensure reliable, secure, and high-quality email delivery through an email API, follow these best practices. These guidelines will help optimize deliverability, maintain security, and create a smooth user experience.

1. Optimize for High Deliverability

Deliverability—ensuring that emails reach recipients’ inboxes rather than spam folders—is critical to any email integration. Here’s how to optimize it:

  • Use a Consistent Sender Address: Avoid changing the sender email frequently, as this can trigger spam filters. Establish a verified domain and sender identity.
  • Authenticate Your Domain: Set up SPF, DKIM, and DMARC records for your domain to authenticate your emails. These standards help prove the authenticity of your messages, boosting your reputation with email providers.
  • Avoid Spam Trigger Words: Be cautious with promotional language, excessive punctuation, or ALL CAPS, as these can increase the likelihood of emails being flagged as spam.
  • Monitor Bounce Rates and Engagement: Track open rates, click-through rates, and bounces. High bounce rates or low engagement can hurt deliverability; remove inactive or invalid email addresses from your lists regularly.

2. Secure Your API Credentials and Data

Email APIs often require sensitive data, so prioritizing security is essential:

  • Store API Credentials Securely: Avoid hardcoding API keys in your application code. Instead, use environment variables to store sensitive data securely.
  • Use HTTPS for API Calls: Ensure all interactions with the email API occur over HTTPS to protect data in transit.
  • Enable Authentication: Some email APIs support OAuth for secure user authentication. This allows you to access users’ email accounts without requiring their passwords, enhancing data security.
  • Access Control: If multiple users access the API, restrict permissions based on role requirements and follow the principle of least privilege.

3. Handle Errors and Retries Gracefully

Ensuring that your email-sending process is reliable involves handling errors and retries efficiently:

  • Set Up Error Handling: Implement error-handling mechanisms to catch issues like invalid recipient addresses, missing fields, or authentication failures. Log errors for troubleshooting and monitor the frequency of specific issues.
  • Retry Logic for Temporary Failures: In cases of network issues or temporary API errors, implement retry logic to resend the email a few times before giving up. Avoid continuous retries, which can trigger rate limits or duplicate emails.
  • Manage Rate Limits: Email APIs may enforce rate limits on requests. Monitor these limits and use rate-limiting strategies in your application to prevent interruptions.

4. Personalize and Format Emails for Better Engagement

Personalized, well-formatted emails are more engaging and less likely to be flagged as spam:

  • Use Dynamic Content: Personalize emails based on user data (e.g., name, recent activity) to increase relevance and engagement.
  • HTML and Plain Text Versions: Include both HTML and plain text versions of your email content. This ensures that your message is accessible on any device and client, and it also reduces the chance of being flagged as spam.
  • Optimize for Mobile: Ensure email templates are responsive to accommodate users on mobile devices.

5. Log and Monitor API Activity

Tracking API usage and performance is crucial for maintaining a smooth integration:

  • Log Requests and Responses: Keep logs of API requests and responses to help with debugging and performance analysis.
  • Set Up Monitoring and Alerts: Use monitoring tools to track the success rate of email deliveries, and set up alerts for failures or unusual activity, such as sudden spikes in email volume.
  • Analyze Engagement Metrics: Regularly review engagement metrics (e.g., open rates, click rates) to assess the effectiveness of your emails and adjust content as needed.

6. Test Before Sending to Users

Test thoroughly to ensure that emails appear as intended and that the API integration is reliable:

  • Use a Testing Environment: Configure a testing environment to simulate real email sends without affecting actual users.
  • Send Test Emails: Test email templates and functionality to different email providers (Gmail, Outlook, Yahoo) to verify formatting and deliverability.
  • Check for Broken Links and Missing Content: Review each test email to ensure that links, images, and dynamic content load properly and that no information is missing.

Troubleshooting Common Issues

Integrating an email API can sometimes involve challenges, especially when dealing with large volumes or various technical requirements. Here are some common issues you might encounter and strategies for troubleshooting them effectively.

1. Handling API Rate Limits

Most email APIs enforce rate limits to prevent abuse and ensure consistent performance for all users. Exceeding these limits can result in errors or temporary suspension of requests.

  • Solution: Monitor your API usage and implement rate limiting within your application to stay within allowed thresholds. If you need higher limits, check with your API provider about upgrading your plan.
  • Retry Logic: Implement exponential backoff retry logic to avoid hitting the rate limit repeatedly. For example, wait a few seconds before resending the request, and increase the wait time with each retry attempt.

2. Resolving Authentication Errors

Authentication errors occur when the API credentials are incorrect or expired, often resulting in 401 (Unauthorized) responses.

  • Solution: Double-check your API keys, client ID, and access token. Make sure these are stored securely in environment variables and not hardcoded.
  • Token Refresh: If using an access token that expires, implement a token refresh mechanism to ensure your application maintains access to the API without interruption.

3. Addressing Invalid Email Errors

Invalid email addresses or improperly formatted requests can cause errors when sending emails.

  • Solution: Validate email addresses before sending them to the API to reduce the chances of invalid email errors. Regularly clean up your email lists to remove outdated or incorrect addresses.
  • Error Logging: Log any invalid email errors for later review and possible correction. This will help you identify recurring issues and prevent similar errors in future sends.

4. Managing Temporary Network Failures

Network issues can disrupt API requests and cause temporary failures in email delivery.

  • Solution: Implement retry logic to automatically resend requests that fail due to network issues. Use a maximum retry limit to avoid excessive attempts, and log the failures for later review if retries are unsuccessful.
  • Timeout Settings: Set a reasonable timeout for your API requests to prevent prolonged network-related delays.

5. Debugging Content-Related Issues

Sometimes, emails with specific content (e.g., large images, special characters) may fail to send or get flagged as spam.

  • Solution: Review email content for any problematic elements, such as overly large attachments, unsupported characters, or HTML/CSS that may not render correctly. Ensure attachments meet the API’s size and format requirements.
  • Content Testing: Test emails with different email clients and devices to verify that they display as expected and are not flagged as spam due to formatting issues.

6. Troubleshooting Deliverability Issues

Low deliverability can be a complex issue, often resulting in emails being marked as spam or blocked by certain email providers.

  • Solution: Set up proper authentication (SPF, DKIM, DMARC) for your sending domain to improve trustworthiness. Avoid spam trigger words, and monitor bounce rates to keep your sending reputation strong.
  • Monitoring Tools: Use deliverability monitoring tools to track where emails land (inbox vs. spam) and to gather insights on how to improve delivery success.

7. Handling Duplicate Emails

Duplicate emails can occur due to retry logic or unintended resends, which can negatively impact the user experience.

  • Solution: Implement deduplication checks within your application logic to prevent the same email from being sent multiple times. You can also add unique message IDs or timestamps to track and prevent duplicates effectively.

8. Monitoring Error Responses for Insights

Email APIs often return detailed error responses that can help you identify specific issues and resolve them quickly.

  • Solution: Regularly review and log error responses from the API to understand common issues. Use these insights to adjust your code or content, improving the reliability of your email-sending process.

By proactively addressing these common issues and implementing robust error-handling mechanisms, you can ensure a more reliable and user-friendly email-sending experience. Following these troubleshooting steps will help you maintain smooth, consistent email operations and reduce potential disruptions in your application.

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