Download File From Email With OpenPop.Pop3

Article Overview

Background

Connect and Authenticate with Email Server
Get email content and file from the email
Download or save attached/email file

Pre-requisites
How to download or save file from email

Connect with Server
Authenticate to Server
Get email content of a particular one email
Get file from email content
Download file
Save email file on the server

Complete example

References, Model
Connect and authenticate with server
Get email content and attachment file from email
Get file from email content
Download or save attached file
Output

Summary

Background

There was a requirement where I had to read an email from an email box and after that, I had to download or save a file from the email. There are various libraries using which you can implement this. I have used OpenPop.NET which is a robust open-source POP3 client and MIME parser written in C#. Hence, I had to customize searched solutions in an effective and easy way.

This article mainly focuses on three key things:

Connect and Authenticate with Email Server
Get email content and file from the email
Download or save attached/email file

Here, I have kept all the implementation details along with a complete example.

Prerequisites

You MUST have basic knowledge of C#, ASP .NET, and Email Parsing.
Download “OpenPop.dll” from OpenPop.NET.
You MUST have gone through my earlier article Email Parsing With OpenPop.Pop3 (OpenPop.NET)

How to download a file from email

There are mainly six steps to perform this,

Connect with Server
Authenticate to Server
Get email content of a particular one email
Get file from email content
Download file
Save email file on the server

Now, let us see in detail.

Connect with Server

You need host (server) name, port number, etc. details to connect with the POP3 email server.

Pop3Client objPOP3Client = new Pop3Client();
objPOP3Client.Connect(host, port, useSsl);

Authenticate to Server

Once the server is connected you have to authenticate it using email (username) and password. This is your email box login details.

objPOP3Client.Authenticate(user, password);

Get email content of a particular one email

After successful authentication, you have to get email content of a particular one email using message number.

MessageModel message = GetEmailContent(messageNumber, ref objPOP3Client);
objMessage = objPOP3Client.GetMessage(intMessageNumber);

Get file from email content

Now, you can process email content and find all attachments. For, easy to understand I have taken first attachment file you can perform for loop to process on all files.

List<MessagePart> attachment = objMessage.FindAllAttachments();
message.FileName = attachment[0].FileName.Trim();
message.Attachment = attachment;

Download file

Now, you have to download attachment using byte array and write it to response using binary write.

downloadFile(message);
byte[] content = attachment[0].Body;
Response.AddHeader("content-disposition", "attachment; filename=" + message.FileName);
Response.BinaryWrite(content);

Save email file on the server

Actually, you can also save the file on the server also, instead of download. This can be done by file write all bytes to a specific folder path.

File.WriteAllBytes(Path.Combine(HttpRuntime.AppDomainAppPath, "Files/") + message.FileName, attachment[0].Body);

Here, I have given high-level steps for our implementation. Now, let us see the complete example which will give you more clarity about these steps.

Complete example

For the complete example, I have prepared and uploaded a web site which contains all the code.

References, Model
Connect and authenticate with the server
Get email content
Get attachment file from email
Download or save the attached file
Output

References, Model

Include the dll reference and message model class.

using System;
using System.Collections.Generic;
//add references of OpenPop
using OpenPop.Mime;
using OpenPop.Pop3;

public class MessageModel
{
public string MessageID;
public string FromID;
public string FromName;
public string Subject;
public string Body;
public string Html;
public string FileName;
public List<MessagePart> Attachment;
}

Connect and authenticate with serve

protected void Page_Load(object sender, EventArgs e)
{
Pop3Client objPOP3Client = new Pop3Client();
string host = "hostname", user = "username", password = "userpassword";
int port = 110;
bool useSsl = false;
try
{
objPOP3Client.Connect(host, port, useSsl);
objPOP3Client.Authenticate(user, password);
int messageNumber = 19;//
MessageModel message = GetEmailContent(messageNumber, ref objPOP3Client);
if (message != null)
{
downloadFile(message);
}
}
catch (Exception ex)
{
}
finally
{
objPOP3Client.Disconnect();
}
}

Get email content and get attachment file from email

public MessageModel GetEmailContent(int messageNumber, ref Pop3Client objPOP3Client)
{
MessageModel message = new MessageModel();
MessagePart plainTextPart = null, HTMLTextPart = null;
Message objMessage = objPOP3Client.GetMessage(messageNumber);
message.MessageID = objMessage.Headers.MessageId == null ? "" : objMessage.Headers.MessageId.Trim();
message.FromID = objMessage.Headers.From.Address.Trim();
message.FromName = objMessage.Headers.From.DisplayName.Trim();
message.Subject = objMessage.Headers.Subject.Trim();
plainTextPart = objMessage.FindFirstPlainTextVersion();
message.Body = (plainTextPart == null ? "" : plainTextPart.GetBodyAsText().Trim());
HTMLTextPart = objMessage.FindFirstHtmlVersion();
message.Html = (HTMLTextPart == null ? "" : HTMLTextPart.GetBodyAsText().Trim());
List<MessagePart> attachment = objMessage.FindAllAttachments();
if (attachment.Count > 0)
{
message.FileName = attachment[0].FileName.Trim();
message.Attachment = attachment;
}
return message;
}

Download or save attached file

public void downloadFile(MessageModel message)
{
List<MessagePart> attachment = message.Attachment;
try
{
if (attachment[0] != null)
{
byte[] content = attachment[0].Body;
//[1] Save file to server path
//File.WriteAllBytes(Path.Combine(HttpRuntime.AppDomainAppPath, "Files/") + message.FileName, attachment[0].Body);
//[2] Download file
string[] stringParts = message.FileName.Split(new char[] { '.' });
string strType = stringParts[1];
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
Response.AddHeader("content-disposition", "attachment; filename=" + message.FileName);
//Set the content type as file extension type
Response.ContentType = strType;
//attachment[0].ContentType.MediaType;
//Write the file content
Response.BinaryWrite(content);
Response.End();
}
}
catch (Exception ex)
{
}
}

Output

Summary

Now, I believe you will be able to download or save files from email with OpenPop.Pop3 (OpenPop.NET).

10 Comments

Join the conversation! Your thoughts help the community grow.

Simón Zapata5y ago
MessageModel type doesn't exist on OpenPop, where are you getting it from?
- Pankajkumar Patel5y ago
  From OpenPop.NET and it's URL is http://hpop.sourceforge.net/examples.php
Ryder6y ago
Great article...
- Pankajkumar Patel6y ago
  Thanks Ryder for the feedback
Dhruvik Sathvara7y ago
Useful article...
- Pankajkumar Patel7y ago
  Thanks Dhruvik Sathvara for the feedback
Arvind Kataria7y ago
Nice article ... !!!
- Pankajkumar Patel7y ago
  Thanks Arvind Kataria for the feedback
Sourav Kumar Das7y ago
Very Useful Article.
- Pankajkumar Patel7y ago
  Thanks Sourav Kumar Das for the feedback