In this article I will explain with an example, how to send email in ASP Net Core (.Net Core 8) MVC.
Note: For beginners in ASP.Net Core (.Net Core 8) MVC, please refer my article ASP.Net Core 8: Hello World Tutorial with Sample Program example.
 
 

Mail Server Settings in AppSettings.json file

The following Mail Server settings need to be saved in the AppSettings.json file.
Note: It is necessary to use the sender’s email address credentials while defining the Gmail SMTP Server Credentials as Gmail the sender’s email address must be same as the Gmail Username specified in credentials.
 
{
  "Smtp": {
    "Server": "smtp.gmail.com",
    "Port": 587,
    "EnableSsl": true,
    "DefaultCredentials": true,
    "From": "sender@gmail.com",
    "Username": "sender@gmail.com",
    "Password": "GMAILor2STEP-PASSWORD"
  }
}
 
 

Sending Email using Gmail SMTP

MailMessage class properties

Following are the required properties of the MailMessage 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.
IsBodyHtml – Specify whether body contains text or HTML mark up.
Attachments – Attachments. (If any)
ReplyTo – ReplyTo Email address.
 

SMTP class properties

Following are the properties of the SMTP class.
Host – SMTP Server URL. (Gmail: smtp.gmail.com)
EnableSsl – Specify whether your host accepts SSL Connections. (Gmail: True)
UseDefaultCredentials – Set to True in order to allow authentication based on the Credentials of the Account used to send emails.
Credentials – Valid login credentials for the SMTP server. (Gmail: email address and password)
Port – Port Number of the SMTP server. (Gmail: 587)
 
 

Model

The Model class consists of the following properties.
public class EmailModel
{
    public string To { get; set; }
    public string Subject { get; set; }
    public string Body { get; set; }
}
 
 

Namespaces

You will need to import the following namespaces.
using System.Net;
using System.Net.Mail;
using Microsoft.Extensions.Configuration;
 
 

Controller

The Controller consists of following Action methods.

Action method for handling GET operation

Inside this Action method, simply the View is returned.
 

Action method for handling POST operation

Inside this Action method, the posted values are captured through the EmailModel class object.
All the fetched values are set into an object of the MailMessage class object.

Setting Body of Email

The Body of the email is Text (Non HTML) hence the IsBodyHtml property of the MailMessage class object is set to FALSE.

Sending Email

Then, an object of the SmtpClient class is created and the values of Host, Port, DefaultCredentials and EnableSsl are fetched from the SMTP section of the AppSettings.json file and are set in respective properties of the SmtpClient class object.
And Username and Password values are passed as parameter to NetworkCredential class from the SMTP section of the AppSettings.json file.
Finally, the email is being sent using Send method of SmtpClient class object and a success message is set to a ViewBag object.
public class HomeController : Controller
{
    public IConfiguration  Configuration { get; set; }
    public HomeController(IConfiguration configuration)
    {
        this.Configuration = configuration;
    }
 
    public IActionResult Index()
    {
        return View();
    }
 
    [HttpPost]
    public IActionResult Index(EmailModel model)
    {
        //Read SMTP section fromAppSetting.json.
        string host = this.Configuration.GetValue<string>("Smtp:Server");
        int port = this.Configuration.GetValue<int>("Smtp:Port");
        bool enableSsl = this.Configuration.GetValue<bool>("Smtp:EnableSsl");
        bool defaultCredentials = this.Configuration.GetValue<bool>("Smtp:DefaultCredentials");
 
        using (MailMessage mm = new MailMessage(model.Email, model.To))
        {
            mm.Subject = model.Subject;
            mm.Body = model.Body;
            mm.IsBodyHtml = false;
            if (model.Attachment != null)
            {
                string fileName = Path.GetFileName(model.Attachment.FileName);
                mm.Attachments.Add(new Attachment(model.Attachment.OpenReadStream(), fileName));
            }
            using (SmtpClient smtp = new SmtpClient())
            {
                smtp.Host = host;
                smtp.Port = port;
                smtp.EnableSsl = enableSsl;
                smtp.UseDefaultCredentials = defaultCredentials;
                NetworkCredential networkCred = new NetworkCredential(model.Email, model.Password);
                smtp.Credentials = networkCred;
                smtp.Send(mm);
            }
        }
        ViewBag.Message = "Email sent.";
        return View();
    }
}
 
 

View

Inside the View, in the very first line the EmailModel class is declared as model for the View.
The View consists of an HTML Form which has been created using the following TagHelpers attributes.
asp-action – Name of the Action. In this case the name is Index.
asp-controller – Name of the Controller. In this case the name is Home.
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.
When the Send Button is clicked, the Form gets submitted and the Model object is sent to the Controller.
Note: For more details in Form Submission in ASP.Net Core MVC, please refer ASP.Net Core: Form Submit (Post) Example.
 
Finally, the ViewBag 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.
 
@model Send_Email_Core_MVC.Models.EmailModel
@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" asp-controller="Home" asp-action="Index">
        <table border="0" cellpadding="0" cellspacing="0">
            <tr>
                <td style="width: 80px">To:</td>
                <td><input type="text" asp-for="To" /></td>
            </tr>
            <tr>
                <td>Subject:</td>
                <td><input type="text" asp-for="Subject" /></td>
            </tr>
            <tr>
                <td valign="top">Body:</td>
                <td><textarea cols="20" rows="3" asp-for="Body"></textarea></td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" value="Send" /></td>
            </tr>
        </table>
    </form>
    @if (ViewBag.Message != null)
    {
        <script type="text/javascript">
            window.onload = function () {
                alert("@ViewBag.Message");
            };
        </script>
    }
</body>
</html>
 
 

Possible Errors

The following error occurs when you try to send email using Gmail credentials in your application.
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
 
Exception Details: System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
 

Solution

GMAIL Error: The SMTP server requires a secure connection or the client was not authenticated
 
 

Screenshot

Email Form

ASP.Net Core: Send Email with example
 

Received Email

ASP.Net Core: Send Email with example
 
 

Downloads

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