The Basics of Sending Emails
It’s hard to imagine a modern person who doesn’t incorporate software products into their daily life. We use digital solutions in various forms: from tools to perform our jobs to entertainment platforms. And naturally many applications need to communicate with us, even when we are away from keyboard. They convey certain information: confirmations, notifications, newsletters, and many other messages.
Many applications use push notifications to communicate with their users. But this can be inconvenient because users need to check the app often to stay updated. A better, more reliable option is sending emails to keep users informed.
C# is a time-proven and respectable programming language used by many developers. On that account, we will cover the C# email-sending logic in this article. Keep reading!
Sending Emails in C# Using SMTP
The standard approach to sending an email in C# is using SMTP (Simple Mail Transfer Protocol). It is a standard network protocol used to send emails over the internet.
However, C# by itself doesn't include the functionality to interact with email servers. You would need to handle low-level operations, such as connecting to SMTP servers, formatting email messages, and managing network sockets. It may be a cumbersome and error-prone approach.
Instead, C# relies on .NET to cope with email sending. .NET is an open-source developer framework that offers pre-built classes and libraries for secure and efficient execution of C# programs.
Let’s go through a step-by-step guide on sending emails in C# using SMTP.
- Add required namespaces
Firsthand, we add the necessary namespaces.
using System.Net; // Provides classes for network operations. |
- Configure the SMTP Client
The SmtpClient class is responsible for connecting to the SMTP server and sending the email. Let’s consider Gmail as our example SMTP Server Address. Here’s how to configure it:
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com") |
- Create the email content
Next, we use the MailMessage class to compose a new message.
MailMessage mailMessage = new MailMessage |
- Send the email
Use the Send() method of the SmtpClient class to send the email. Make sure to handle errors with a try-catch block.
try |
Note: This example contains placeholder data (email addresses, password, and email content). Replace these with your actual values to make it work for your case.
Sending emails in C# with the SmtpClient class is a working solution, but it is considered outdated. Microsoft has deprecated SmtpClient for modern development. Instead, we recommend using advanced libraries like MailKit or an external ESP like UniOne SMTP API service, which provide improved flexibility, better security, and top speed.
We will cover the email-sending process in C# using MailKit and UniOne in the next sections!
Sending Emails in C# with MailKit
While SmtpClient still works for simple use cases, large-scale applications require different approaches. It’s crucial to choose libraries that offer better performance, scalability, and security. One of the most reliable modern solutions is MailKit. MailKit is a popular and robust library for working with emails in C#. It supports asynchronous operations, various email protocols, and more. MailKit is a perfect solution for sending, receiving, and managing emails in .NET applications.
Let’s take a look at how the email-sending flow in C# works with MailKit.
- Install MailKit
First, add the MailKit package to your project. You can do this through NuGet Package Manager or via the Package Manager Console:
Install-Package MailKit |
- Add required namespaces
using MailKit.Net.Smtp; |
- Create the email
Create a MimeMessage to set up the email content:
var emailMessage = new MimeMessage(); |
- Configure the SMTP Client
Create an SmtpClient and connect to the SMTP server. Configure it with the appropriate server address and authentication details:
using (var smtpClient = new SmtpClient()) |
- Handle exceptions
It’s important to handle any potential exceptions that may occur:
try |
We’re done! Below is the complete code example on sending emails in C# using MailKit:
using MailKit.Net.Smtp; |
Sending Emails in C# Using UniOne’s Email API
What we covered earlier is the traditional method of sending emails in C# via an SMTP server, either local or third-party. While it works fine, it’s not as efficient or seamless as using dedicated email services, which typically offer automation, analytics, and tons of other useful features.
When choosing a suitable service, you might want to consider the UniOne Email API service. UniOne allows you to utilize the power of SMTP in just minutes by setting the required authentication credentials in your software. Once done, you’re all set to send emails effortlessly through your app's SMTP connection. UniOne’s SMTP API offers maximum simplicity while also providing access to additional powerful and customizable features, including:
- Sending up to 150,000 emails per hour (with Web API for more)
- Using variable substitution, unsubscribe links, and click tracking
- Sending emails up to 10 MB in size
- Personalizing emails with templates
- Organizing campaigns into independent projects
- Getting real-time updates with UniOne webhooks and more
Whether it's for marketing campaigns, transactional alerts, newsletters, or promotions, UniOne handles a wide range of email types.
Many ESPs, including UniOne, offer multiple APIs for email submission, the most widespread being SMTP API and HTTP API. SMTP API is very similar to the basic SMTP connection described above but still provides access to the service’s advanced features through the use of custom email headers. HTTP API is far more versatile and powerful but also more complex to integrate.
Below is a tutorial for sending emails in C# using UniOne’s HTTP API:
- Configuration Setup
Before you can send emails, you need to configure your application with the necessary credentials. This involves setting the server address (between EU or US servers, choose the one you’ve registered at) and the API key.
var json = "{\"UniOne\":{" + |
- Creating the Email
Now, you define the email message, including the sender's email, recipient's email, subject, and body content.
var msg = new EmailMessageData { |
- Sending the Email
To send the email, you use the Send method from the UniOne API client.
var email = await uniOne.Email.Send(msg); |
And that’s it! The full code looks like this:
using System.Text; |
We covered the basics on how to configure the API, create an email message with dynamic content, send it, and handle the result using the UniOne API. For further details, consult the UniOne C# library documentation.
HTML Email Sending in C#
Sending HTML emails in C# is a common task for applications that need to send newsletters, notifications, or promotional emails. HTML emails allow you to include special formatting, images, links, and other elements that make the message more engaging.
While System.Net.Mail is a good fit for basic email sending, MailKit is the superior choice. We will cover the MailKit approach in this guide.
- Install MailKit
Install MailKit via NuGet:
Install-Package MailKit |
- Create a Send Email Function
using MailKit.Net.Smtp; // SMTP client to send the email |
- Usage Example
Here’s how to use the SendHtmlEmail function to send an HTML email:
// HTML content for the email |
Using MailKit to send HTML emails is straightforward and flexible. It offers modern features like attachments, inline images, and enhanced security. It’s a great choice for handling complex email tasks in your C# applications.
How to Attach Files to Emails Using C#
To send an email with an attachment using MailKit in C#, you first create a MimeMessage object that represents the email, setting the sender, recipient, subject, and body content.
You can specify the body as HTML using the BodyBuilder class. To attach a file, simply add it to the BodyBuilder using the Attachments.Add() method. The SmtpClient class is then used to connect to an SMTP server, authenticate with your credentials, send the email, and disconnect once the email is sent. Below is an example of how to implement this in code:
using MailKit.Net.Smtp; |
Setting Up Email Configuration in the Web.Config File
Setting up email configuration in the web.config file makes it easier to update and maintain in your project. It also enables the encryption of sensitive information, such as email credentials.
Note that if you're using MailKit for sending emails, SMTP settings won't be configured in the web.config file as they are with SmtpClient. Instead, you'll configure them directly in your C# code.
To set up email configuration in the web.config file for a C# application, you can store your SMTP settings under the section:
<configuration> |
Done! Replace placeholder values above and use the SmtpClient class to send emails.
Sending Emails to Multiple Recipients in C#
When deciding on the best approach for sending emails to multiple recipients in C#, the choice depends on the complexity of your use case. SMTP client (SmtpClient class) is enough for sending plain text emails. But if your application has advanced needs, MailKit is the preferred solution.
Now, let’s explore how to send emails to multiple recipients in C# using MailKit.
- Creating a MimeMessage and Setting the Sender
In this step we create a MimeMessage object and set the sender’s email address.
var emailMessage = new MimeMessage(); |
- Using InternetAddressList for Recipients
MailKit provides a way to work with a list of email addresses using the InternetAddressList class. It provides a collection-based approach to handle multiple email addresses and is particularly useful when you need to add multiple recipients at once without calling Add() individually for each recipient.
var recipients = new InternetAddressList(); |
- Assigning the Recipients to the To Field
The AddRange() method of the MimeMessage object is used to add the entire InternetAddressList to the To field.
emailMessage.To.AddRange(recipients); |
And this is it! We have assigned multiple recipients for the email.
Why Testing Emails is Crucial in C# and How to Do It
Testing emails is essential to ensure they are delivered properly, formatted correctly, and secure.
How to Test Email sending in C#:
- “Fake” Email Servers: Tools like Papercut or MailHog let you capture and view test emails without sending them to real recipients.
- Staging Environment: Use real SMTP servers like Gmail to check email delivery and formatting in a controlled setting.
- Third-Party Testing Tools: ESPs like UniOne offer powerful features for testing, including their SMTP Debug Tools, test recipients and many more.
Сonclusion
In this article, we covered various aspects of email sending in C#, ranging from the reliable but outdated .NET approach to modern third-party services. The classic .NET approach works well for small applications with basic email functionality, but scalable, modern applications often call for more advanced solutions, such as UniOne.
The UniOne SMTP API service offers powerful features, clear documentation, and 24/7 support. Additionally, UniOne provides newcomers with a generous 4-month free trial, including many custom features.
We hope you found this article helpful – thanks for reading!
FAQ
What are the limitations of sending emails using SMTP in C#?
Sending emails via SMTP in C# can work, but it comes with a few drawbacks:
- Performance Issues: The .NET SmtpClient is synchronous by default, meaning it processes emails one at a time. This can lead to delays, especially when sending large volumes of email.
- Security Concerns: Hardcoding SMTP credentials is risky, as they can be exposed if not handled securely. Also, sending credentials in plaintext without encryption (like TLS/SSL) can put sensitive data at risk.
- Deliverability Issues: Emails may end up in the spam folder if you don’t have email authentication (SPF, DKIM, and DMARC) set up for your sender domain. This is done by adding the required DNS entries.
- Deprecation: In .NET Core and .NET 5+, SmtpClient is considered obsolete. Microsoft recommends using alternatives like MailKit for better features and support.
For larger-scale or production environments, it’s a must to switch into using modern services. and UniOne would be the perfect choice.
Is C# good for email sending in large-scale applications?
C# can be a good choice for sending emails in large-scale applications, but its effectiveness depends on how you implement the email-sending functionality. While the language itself is robust, the built-in SmtpClient class in .NET is not ideal for large-scale systems.
For this scenario, use C# with third-party libraries or APIs from email service providers (e.g. UniOne Email API service). These providers handle delivery, scaling, and analytics, while C# serves as the backend language to manage email logic and integration.
Can I send emails asynchronously in C#?
Yes, you can send emails asynchronously in C# by using modern libraries like MailKit or services like UniOne, which provide built-in asynchronous methods. While the older SmtpClient in .NET also has an asynchronous SendMailAsync method, it is considered outdated and less efficient compared to modern alternatives.
How can I use C# for secure email sending?
To use encrypted SMTP connection in C# for secure email sending, you need to enable encryption (TLS or SSL) and use the proper port number (465 for SSL or 587 for TLS). Nowadays most SMTP servers do not support unencrypted connections at all, so this is not much of a problem.