In this article I will explain with an example, how to send email with attachment from a specific URL in ASP.Net Core (.Net Core) Razor Pages.
PDF File URL
The following
PDF file will be used in this article for sending as attachment with email.
![ASP.Net Core Razor Pages: Send email with attachment from a specific URL]()
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,
"EnableSsl": true,
"DefaultCredentials": false
}
}
Sending email with attachment from URL
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.
SmtpClient class methods
Following are the methods of the SMTP class.
Host – SMTP Server URL (Gmail: smtp.gmail.com)
Port – Port Number of the SMTP sever (Gmail: 587)
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)
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 System.Net;
using System.Net.Mail;
Razor PageModel (Code-Behind)
The PageModel consists of the 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 accepts EmailModel class as a parameter.
This Handler method gets called, when Send Button is clicked the Security Protocol is set.
Then, the GET request is made using GetStreamAsync method of HttpClient class and the response is stored in a Stream class object.
After that, the Recipient email address (toAddress), the Sender email address (fromAddress), Subject and Body values are fetched from their respective fields and are set into an object of the MailMessage class.
Setting Body of Email
The Body of the email is Text (Non HTML) hence the IsBodyHtml property of MailMessage class is set to FALSE.
Attaching File
The Stream class object is passed as parameter to new object of Attachment class along with the file name which is ultimately assigned to the MailMessage class object.
Sending Email
Then, an object of the SmtpClient class is created and the values of Host, Port, EnableSsl and UseDefaultCredentials are fetched from the SMTP section of the AppSettings.json file and set to the respective properties of SmtpClient class along with the Credentials.
Finally, the email is being sent and success message is set into a
ViewData object.
C#
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)
{
//Setting TLS 1.2 protocol.
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
using (HttpClient client = new HttpClient())
{
string apiUrl = "https://raw.githubusercontent.com/aspsnippets/test/master/Sample.pdf";
//Read the file to Stream from URL.
using (Stream stream = client.GetStreamAsync(apiUrl).Result)
{
//Read SMTP section from AppSettings.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;
//Attaching file from URL.
mm.Attachments.Add(new Attachment(stream, Path.GetFileName(apiUrl)));
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);
}
}
ViewData["Message"] = "Email sent.";
}
}
}
}
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 Send 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, the
ViewData object 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 Email_Attachment_URL_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" enctype="multipart/form-data">
<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 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
Screenshots
Email Form
![ASP.Net Core Razor Pages: Send email with attachment from a specific URL]()
Received Email
![ASP.Net Core Razor Pages: Send email with attachment from a specific URL]()
Downloads
