How to Send email using C# and Gmail

hey everyone! Today we are going to be writing a simple application in CSharp that can send emails!

This application is going to be a simple little SMTP Client that will interface with Gmail’s Servers using your username and password. Since this is a pretty simple task, there isn’t a whole lot of code, so it’s a great project to start learning with!

Alright! Let’s get right into building the application!
In this tutorial, I’m going to be using the Devexpress components. They work just like the default windows components, they just look a little better.
The code behind is what is important and it will look almost identical regardless of the form controls.

Alright!! Now we have our form completed! It’s time to write some code!

First, we are gonna double-click on the send button, this will generate an event handler which we will put the code to send the email inside of.

The first line of code we are going to write will create a new NetworkCredential object called login. This will be used to pass the username/password to Gmail.

workCredential login = new NetworkCredential(txtUsername.Text, txtPassword.Text);

Next we will need to create an SMTPClient object which will actually send the message. This line looks like the following:

mtpClient client = new SmtpClient(txtSMTP.Text);

After writing that line, you will get an error and have to import System.Net.Mail. That line looks like this:

using System.Net.Mail;

After you have that setup, it is time to set our client up so it can send the message. The first setting we are going to set is the Port number. This needs to match google’s port number which is 587. This line converts our textbox’s text to an integer (variable type for numbers) and sets the client’s port to the number stored in our port textbox.

Client.Port = Convert.ToInt32(txtPort.Text);

Our next thing will be to enable SSL. Google requires SSL be enabled to use Gmail. So that code looks like this:

client.EnableSSL = true;

The last thing we are going to do is pass the credentials to the new client object and thanks to previously creating the login variable, that line looks like this:

client.Credentials = login;

Now that our client is setup, we just need to create the mail addresses and we will be ready to form our message! The code to create our mail addresses is listed below.

MailAddress sendAddr = new MailAddress(txtUsername.Text);
MailAddress recAddr = new MailAddress(txtSendTo.Text);

Next, we will need to create a new Mail Message, this is the actual content of the message.

I’m going to explain each line in paragraph form and then show the block of code after so it will be easier to copy/paste.

First, we create the object, passing it the sender and receiver addresses. After that, we pass the subject textbox’s text property as the subject. Then we pass the memo edit’s (or textbox if you used that instead) text property as the body. After that, we set the BodyEncoding to UTF8, I wouldn’t worry about this, it’s just a character encoding type. IsBodyHTML is just used to tell if the email contains HTML markup or not, I used true for this and it worked fine. Priority seems like a silly property but normal makes the most sense. Lastly, DeliveryNotificationOptions will notify you if the message fails to send.

MailMessage msg = MailMessage(sendAddr, recAddr);
msg.Subject = txtSubject.Text;
msg.Body = memBody.Text;
msg.BodyEncoding = Encoding.UTF8;
msg.IsBodyHtml = true;
msg.Priority = MailPriority.Normal;
msg.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;

Alright! That was a huge block of code and we are almost there! Your code should look something like this now!

Now we need to set up the Send Completed event handler. This isn’t totally necessary but it is nice that our application will be able to display an error if the send fails.

Below DeliveryNotificationOptions, we need to add the following code:

client.SendCompleted += new SendCompletedEventHandler(sendCallback);

This line will call the sendCallback function with a result. Now we just need to write that function!

private static void sendCallback(object sender, AsyncCompletedEventArgs e)
{
    if (e.Cancelled || e.Error != null)
     {
         MessageBox.Show("Error sending Email!");
     }
     else
     {
         MessageBox.Show("Sent Successfully!");
      }
}

This will show an error message or success message depending on the result!

Our very last lines will be the lines to send the email! This will be added back inside of our click event handler below the SendCompleted line!

string userToken = "sending"
client.SendAsync(msg, userToken);

The resulting code will look like this, sorry the box cuts off a little bit of the sendCallback code.

Once you have the code in place it is time to give it a test run! We have to change one setting in google to make this work. Google “Low Security Applications”, the top link should be a support.google.com link.

After that, you need to click Less Secure App Access and allow Less secure Apps.

Without this option turned on, Google will not send your emails!

Once that is all set up, build your application and fill it out, this is what my application looked like all filled out!

Once I hit the send button, the email sent! This is my test email that worked. Thanks for reading, I really hope this helped you out! If you have any questions, let me know in the comments below!!