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c# – Sending email from webhosting without having to use username and password

Posted by: admin July 12, 2020 Leave a comment


I have written a C# program to send an email, which works perfectly.
Additionally, I have a PHP script to send emails, which works perfectly aswell.

But my question is :
Is it possible to send an email with C# like you do from PHP where you don’t need to specify credentials, server, ports, etc.

I would like to use C# instead of PHP, because I am creating an ASP.Net web application.

This is my current C# code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

using System.Net.Mail;
using System.Net;

namespace $rootnamespace$
public partial class $safeitemname$ : Form
    public $safeitemname$()

    private void AttachB_Click(object sender, EventArgs e)
        if (AttachDia.ShowDialog() == DialogResult.OK)
            string AttachF1 = AttachDia.FileName.ToString();
            AttachTB.Text = AttachF1;
            AttachPB.Visible = true;
            AttachIIB.Visible = true;
            AttachB.Visible = false;

    private void AttachIIB_Click(object sender, EventArgs e)
        if (AttachDia.ShowDialog() == DialogResult.OK)
            string AttachF1 = AttachDia.FileName.ToString();
            AttachIITB.Text = AttachF1;
            AttachPB.Visible = true;


    private void SendB_Click(object sender, EventArgs e)
            SmtpClient client = new SmtpClient(EmailSmtpAdresTB.Text);
            client.EnableSsl = true;
            client.Timeout = 20000;
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            client.UseDefaultCredentials = false;
            client.Credentials = new NetworkCredential(EmailUserNameTB.Text, EmailUserPasswordTB.Text);
            MailMessage Msg = new MailMessage();
            Msg.From = new MailAddress(SendFromTB.Text);
            Msg.Subject = SubjectTB.Text;
            Msg.Body = EmailTB.Text;

            /// Add Attachments to mail or Not
            if (AttachTB.Text == "")
                if (EmailSmtpPortTB.Text != null)
                    client.Port = System.Convert.ToInt32(EmailSmtpPortTB.Text);

                MessageBox.Show("Successfuly Send Message !");
                Msg.Attachments.Add(new Attachment(AttachTB.Text));
                Msg.Attachments.Add(new Attachment(AttachIITB.Text));
                if (EmailSmtpPortTB.Text != null)
                client.Port = System.Convert.ToInt32(EmailSmtpPortTB.Text);

                MessageBox.Show("Successfuly Send Message !");

        catch (Exception ex)

    private void settingsBindingNavigatorSaveItem_Click(object sender, EventArgs e)


    private void awDushiHomesEmail_Load(object sender, EventArgs e)
        // TODO: This line of code loads data into the 'awDushiHomesDBDataSet.Settings' table. You can move, or remove it, as needed.


This is how it is done in PHP:

//define the receiver of the email
$to = '[email protected]';

//define the subject of the email
$subject = 'Test email with attachment';

//create a boundary string. It must be unique
//so we use the MD5 algorithm to generate a random hash
$random_hash = md5(date('r', time()));

//define the headers we want passed. Note that they are separated with \r\n
$headers = "From: [email protected]\r\nReply-To: [email protected]";

//add boundary string and mime type specification
$headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-".$random_hash."\"";

//read the atachment file contents into a string,
//encode it with MIME base64,
//and split it into smaller chunks
$attachment = chunk_split(base64_encode(file_get_contents('PDFs\Doc1.pdf')));

//define the body of the message.
ob_start(); //Turn on output buffering

--PHP-mixed-<?php echo $random_hash; ?> 
Content-Type: multipart/alternative; boundary="PHP-alt-<?php echo $random_hash; ?>"

--PHP-alt-<?php echo $random_hash; ?> 
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Hello World!!!
This is simple text email message.

--PHP-alt-<?php echo $random_hash; ?> 
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

<h2>Hello World!</h2>
<p>This is something with <b>HTML</b> formatting.</p>

--PHP-alt-<?php echo $random_hash; ?>--

--PHP-mixed-<?php echo $random_hash; ?> 
Content-Type: application/zip; name="Doc1.pdf" 
Content-Transfer-Encoding: base64 
Content-Disposition: attachment 

<?php echo $attachment; ?>
--PHP-mixed-<?php echo $random_hash; ?>--

//copy current buffer contents into $message variable and delete current output buffer
$message = ob_get_clean();

//send the email
$mail_sent = @mail( $to, $subject, $message, $headers );
//if the message is sent successfully print "Mail sent". Otherwise print "Mail failed"
echo $mail_sent ? "Mail sent" : "Mail failed";

I’m not asking for you to write my code but maybe you could provide some info or let me know if its possible or not.


My question is not about not using a smtp server but how to send an email without having to enter username and password. I know, that it will only work if the request to send the email comes from my server.

How to&Answers:

The reason why in PHP you can send a mail without specifying SMTP credentials is because someone else already configured php.ini or sendmail.ini for you (files that the php interpreter use to get some values).

This is usually the case with a managed hosting (or if you use php on your dev pc with tools like AMPPS which can make you edit easily the SMTP settings through an UI and forgot it).

In ASP.net / c# there is the app.config or web.config file, where you can inject smtp settings (in the <mailSettings> tag) and therefore achieve the same result as PHP (the SmtpClient will automatically use the credentials stored there).

See these questions for an example:

SmtpClient and app.config system.net configuration

SMTP Authentication with config file's MailSettings


At these posts, to which likely this will be a duplicate of, you will find a couple of ways how to send email using ASP.NET.

Note: You can’t send email without a smtp server, though you don’t need one of your own if someone else let you use their’s.


If you have php installed in your server you can simply send email through php main function. You don’t need credentials.

The built-in email sending function of php is


You can use this code for detail understanding

// recipients
  $to  = "[email protected]"; // note the comma
  // subject
  $subject = 'Testing Email';

  // message
    $message = " Hello, I am sending email";

  // To send HTML mail, the Content-type header must be set
  $headers  = 'MIME-Version: 1.0' . "\r\n";
  $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";

  // Additional headers
  $headers .= 'To: 'Zahir' <'[email protected]'>' . "\r\n";
  $headers .= 'From: Admin | Hello Softs <[email protected]>' . "\r\n";

  // Mail it
  mail($to, $subject, $message, $headers);


Host : localhost
OS : Ubuntu 12.04 +
Language : PHP

Install sendmail in your OS

sudo apt-get install sendmail

Create a file test-mail.php
Write code inside :

$to      = '[email protected]';
$subject = 'Test Mail';
$message = 'hello how are you ?';
$headers = 'From: [email protected]' . "\r\n" .
    'Reply-To: [email protected]' . "\r\n" .
    'X-Mailer: PHP/' . phpversion();

if(mail($to, $subject, $message, $headers)){
    echo "Mail send";
    echo "Not send";

echo "Now here";

Mail will be sent to [email protected]

Note : You don;t need to write username/password.


You can configure the mail settings section within the web.config file in your web application as shown below. If your site is hosted by a third party hosting company, you can ask them for smtp details (smtp username, smtp password, server name or IP and the port number). If you have this configuration in web.config and smtp is enabled (on the server), then you should be able to send emails without specifying the credentials in c# code.

      <smtp from="[email protected]">
        <network password="password01" userName="smtpUsername" host="smtp.server.com" port="25"/>


Can you send mail without SMTP or “without having” credentials : No ..

If you don’t want to write your credentials in your php files(in the development stage) you can use .env


example .env file:


then you can use these env variables in your php files:


Also you can crypt the .env file or set no public access .But these aren’t the most important security concerns someone should care.. If someone breaks into your server,you are already in trouble..

I’m not a .NET MVC developer but you can set environmental variables(in the development stage) too

Anyway you need to write them somewhere or they are already written..And it’s not a big security concern unless you post your code somewhere like github etc..

NOTE THAT:having environmental variables may cause performance problems in the production especially with php