In this article I will explain with an example, how to send email asynchronously using
MailKit library in ASP.Net Core (.Net Core) Razor Pages.
The email will be sent asynchronously using async modifier and await operator.
Installing MailKit package
Mail Server Settings in AppSettings.json file
The mail server settings are saved in the SMTP section as shown below.
{
"Smtp": {
"Server": "smtp.gmail.com",
"Port": 587
}
}
Sending email Asynchronously 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 SMTP 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.
Model
The Model class consists of following properties.
public class EmailModel
{
public string To { get; set; }
public string Subject { get; set; }
public string Body { get; set; }
public string Email { get; set; }
public string Password { get; set; }
}
Namespaces
You will need to import the following namespaces.
using MimeKit;
using MailKit.Net.Smtp;
using MailKit.Security;
Razor PageModel (Code-Behind)
Inside the PageModel the IConfiguration class is injected into the Constructor (HomeController) with using Dependency Injection method.
Finally, the injected object is assigned to the Configuration property.
The PageModel consists of following Handler methods.
Handler method for handling GET operation
This Handler method left empty as it is not required.
Handler method for handling POST operation
This Handler method gets called, when Send Button is clicked which accepts EmailModel class object as parameter.
Inside this Handler method, the Recipient email address (to), the Sender email address (from), Subject, Body and Password values are fetched from their respective fields which will be passed as parameter to SendEmailAsync method.
The SendEmailAsync is executed using the Run method of Task class.
SendEmailAsync
The SendEmailAsync method is an asynchronous method which is created using async modifier.
Inside the SendEmailAsync method all these parameters are set into the respective properties of 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.
After that, Builder class object is assigned to the Body property of MimeMessage class.
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 AppSetting.json file and are passed as parameter to the ConnectAsync 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
ConnectAsync,
AuthenticateAsync,
SendAsync and
DisconnectAsync are executed using
await operator and a success message is set into a
ViewData object.
public class IndexModel : PageModel
{
public EmailModel Model { get; set; }
public IConfiguration Configuration { get; set; }
public IndexModel(IConfiguration _configuration)
{
this.Configuration = _configuration;
}
public void OnGet()
{
}
public void OnPostSendEmail(EmailModel model)
{
//Performing operations asynchronously.
Task.Run(() => this.SendEmailAsync(model.To, model.Email, model.Password, model.Subject, model.Body));
ViewData["Message"] = "Email sent.";
}
private async Task SendEmailAsync(string toAddress, string fromAddress, string password, string subject, string body)
{
//Read SMTP section from AppSettings.json.
string host = this.Configuration.GetValue<string>("Smtp:Server");
int port = this.Configuration.GetValue<int>("Smtp:Port");
using (MimeMessage mm = new MimeMessage())
{
mm.From.Add(new MailboxAddress("Sender", fromAddress));
mm.To.Add(new MailboxAddress("Recipient", toAddress));
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;
await smtp.ConnectAsync(host, port, SecureSocketOptions.Auto);
await smtp.AuthenticateAsync(fromAddress, password);
await smtp.SendAsync(mm);
await smtp.DisconnectAsync(true);
}
}
}
}
Razor Page (HTML)
HTML Markup
Inside the Razor Page, the ASP.Net TagHelpers is inherited.
The Razor Page consists of an HTML Form which has been created using the following TagHelpers attribute.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
The Form consists of HTML TextBox, TextArea and a Submit Button.
The Send Button has been set with the POST Handler method using the asp-page-handler attribute.
Note: In the Razor PageModel, the Handler method name is OnPostSendEmail but here it will be specified as Send when calling from the Razor HTML Page.
Submitting the Form
When the
Send Button is clicked then, the
ViewData object named Message is checked for NULL and if it is not NULL then the value of the object is displayed using
JavaScript Alert Message Box.
@page
@model SendEmail_Mailkit_Async_Core_Razor.Pages.IndexModel
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
</head>
<body>
<form method="post">
<table>
<tr>
<td style="width: 80px">To:</td>
<td><input type="text" asp-for="Model.To" /></td>
</tr>
<tr><td> </td></tr>
<tr>
<td>Subject:</td>
<td><input type="text" asp-for="Model.Subject" /></td>
</tr>
<tr><td> </td></tr>
<tr>
<td valign="top">Body:</td>
<td><textarea cols="20" rows="3" asp-for="Model.Body"></textarea></td>
</tr>
<tr><td> </td></tr>
<tr>
<td>Gmail Email:</td>
<td><input type="text" asp-for="Model.Email" /></td>
</tr>
<tr><td> </td></tr>
<tr>
<td>Gmail Password:</td>
<td><input type="password" asp-for="Model.Password" /></td>
</tr>
<tr><td> </td></tr>
<tr>
<td></td>
<td><input type="submit" value="Send" asp-page-handler="SendEmail" /></td>
</tr>
</table>
</form>
@if (ViewData["Message"] != null)
{
<script type="text/javascript">
window.onload = function () {
alert("@ViewData["Message"]");
};
</script>
}
</body>
</html>
Possible Errors
The possible errors (exceptions) occurring while sending email with
MailKit in .Net are covered in the following article.
Screenshots
Email Form
![ASP.Net Core Razor: Send ASYNC email using MailKit]()
Received Email
![ASP.Net Core Razor: Send ASYNC email using MailKit]()
Downloads
