Sending Email from ASP.NET (C#)

This guide provides a C# code example for sending emails from your ASP.NET website using the local mail server. This is commonly used for contact forms, order confirmations, or system notifications.

Important Prerequisites & Rules

• Create a Mailbox: Before sending email, you must create a valid mailbox in the control panel.
• Authentication Required: You must use SMTP Authentication. Anonymous sending is not allowed.
• "From" Address Matching: To prevent spam, the "From" address of your message must match the SMTP Username you use to authenticate. For example, if you log in as info@mysite.com, the email must be sent from info@mysite.com.

C# Code Example

You can use the built-in System.Net.Mail namespace to send messages. Copy and adapt the snippet below:

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

// Configuration Variables
string smtpHost = "smtp.yourdomain.com";
int smtpPort = 25; // Try port 26 if 25 doesn't work
string smtpUser = "info@yourdomain.com"; // Full email address
string smtpPass = "YourPassword";
string toAddress = "recipient@external-domain.com";

// Create the message
// IMPORTANT: The 'From' address must match the 'smtpUser'
MailMessage msg = new MailMessage(smtpUser, toAddress);
msg.Subject = "Test Subject";
msg.Body = "This is a test email sent from ASP.NET";
msg.IsBodyHtml = true;

// Configure the SMTP client
SmtpClient client = new SmtpClient(smtpHost, smtpPort);
client.UseDefaultCredentials = false;
client.EnableSsl = false; // Local SMTP usually does not require SSL
client.Credentials = new NetworkCredential(smtpUser, smtpPass);

try
{
    // Send the message
    client.Send(msg);
}
catch (Exception ex)
{
    // Handle errors (log them or display to user)
    // Response.Write("Error: " + ex.Message);
}

Troubleshooting

• Port Blocking: If the code times out or fails to connect, try changing the smtpPort from 25 to 26.
• Authentication Error: Ensure your password is correct and that you are using the full email address as the username.