In this article I will explain with an example, how to send email using
MailKit library in Windows Forms (WinForms) Application using C# and VB.Net.
Installing MailKit package
Mail Server Settings in App.Config file
The following Mail Server settings need to be saved in the App.Config file.
<system.net>
<mailSettings>
<smtp deliveryMethod="Network">
<network
host="smtp.gmail.com"
port="587" />
</smtp>
</mailSettings>
</system.net>
Form Design
The Form consists of following controls:
TextBox – For capturing the values of Recipient Email address, Subject, Body, Gmail account email address and Gmail account password.
Button – For sending email.
The Button has been assigned with the Click event handler.
![Send Email using MailKit in Windows Forms]()
Namespaces
You will need to import the following namespaces.
C#
using MimeKit;
using MailKit.Net.Smtp;
using System.Configuration;
using System.Net.Configuration;
using MailKit.Security;
VB.Net
Imports MimeKit
Imports MailKit.Net.Smtp
Imports System.Configuration
Imports System.Net.Configuration
Imports MailKit.Security
Send Email using MailKit
MimeMessage Class Properties
Following are the required properties of the MimeMessage class.
From – Sender’s email address.
To – Recipient(s) Email Address.
CC – Carbon Copies. (If any)
BCC – Blind Carbon Copies. (If any)
Subject – Subject of the Email.
Body – Body of the Email.
Attachments – Attachments. (If any)
ReplyTo – ReplyTo Email address.
SmtpClient Class Methods
Following are the methods of the SmtpClient class.
Connect – The connection to the SMTP Server is established using the domain and the port number.
Authenticate – The username and password of the SMTP Server is authenticated.
Send – The MimeMessage object is passed to it and the email is sent.
Disconnect – Disconnects the connection with SMTP Server.
Send Email using MailKit in Windows Forms
When the Send Button is clicked, the Recipient email address (to), the Sender email address (from), Subject and Body values are fetched from their respective fields and are passed as parameter to SendEmail function.
Inside the SendEmail function all these parameters are set into an object of the MimeMessage class.
Setting Body of Email
For Body, an object of Builder class is created. The Body of the email is Text (Non HTML) hence it is set into the TextBody property of the Builder class object.
Sending Email
Then, an object of the SmtpClient class is created and the values of Host and Port are fetched from the SMTP section of the App.Config file and are passed as parameter to the Connect method along with the SecureSocketOptions set to Auto.
Note: Setting
Auto allows
MailKit service to decide which
SSL or
TLS option to use. Hence, enabling
SSL is not required.
Also, the CheckCertificateRevocation is set to FALSE.
Note: This is optional and must be used only when Certificate errors are occurring.
Finally, the methods of the Mail Server such as Connect, Authenticate, Send and Disconnect are executed and a success message is displayed using MessageBox class.
C#
protected void SendEmail(object sender, EventArgs e)
{
string to = txtTo.Text;
string from = txtEmail.Text;
string password = txtPassword.Text;
string subject = txtSubject.Text;
string body = txtBody.Text;
//Read SMTP section from Web.Config.
SmtpSection smtpSection = (SmtpSection)ConfigurationManager.GetSection("system.net/mailSettings/smtp");
string host = smtpSection.Network.Host;
int port = smtpSection.Network.Port;
using (MimeMessage mm = new MimeMessage())
{
mm.From.Add(new MailboxAddress("Sender", from));
mm.To.Add(new MailboxAddress("Recepient", to));
mm.Subject = subject;
BodyBuilder builder = new BodyBuilder()
{
TextBody = body
};
mm.Body = builder.ToMessageBody();
using (SmtpClient smtp = new SmtpClient())
{
//Set to False to avoid Certificate verification.
smtp.CheckCertificateRevocation = false;
smtp.Connect(host, port, SecureSocketOptions.Auto);
smtp.Authenticate(from, password);
smtp.Send(mm);
smtp.Disconnect(true);
}
}
MessageBox.Show("Email sent.");
}
VB.Net
Private Sub SendEmail(ByVal sender As Object, ByVal e As EventArgs) Handles btnSend.Click
Dim [to] As String = txtTo.Text
Dim from As String = txtEmail.Text
Dim password As String = txtPassword.Text
Dim subject As String = txtSubject.Text
Dim body As String = txtBody.Text
'Read SMTP section from Web.Config.
Dim smtpSection As SmtpSection = CType(ConfigurationManager.GetSection("system.net/mailSettings/smtp"), SmtpSection)
Dim host As String = smtpSection.Network.Host
Dim port As Integer = smtpSection.Network.Port
Using mm As MimeMessage = New MimeMessage()
mm.From.Add(New MailboxAddress("Sender", from))
mm.To.Add(New MailboxAddress("Recepient", [to]))
mm.Subject = subject
Dim builder As BodyBuilder = New BodyBuilder() With {
.TextBody = body
}
mm.Body = builder.ToMessageBody()
Using smtp As SmtpClient = New SmtpClient()
'Set to False to avoid Certificate verification.
smtp.CheckCertificateRevocation = False
smtp.Connect(host, port, SecureSocketOptions.Auto)
smtp.Authenticate(from, password)
smtp.Send(mm)
smtp.Disconnect(True)
End Using
End Using
MessageBox.Show("Email sent.")
End Sub
Possible Errors
The possible errors (exceptions) occurring while sending email with
MailKit in .Net are covered in the following article.
Screenshots
Email Form
![Send Email using MailKit in Windows Forms]()
The received email
![Send Email using MailKit in Windows Forms]()
Downloads
