Email Threading implementation in ImapClient

Whether you are an individual email user or a big company, your inbox may overlfow with messages. It is often challenging to keep track of conversations and their management can quickly become a daunting task. That’s where threading comes to the rescue, allowing us to organize and follow discussions effortlessly.

In this article, we will explore the fundamentals of email threading and provide a comprehensive guide on utilizing the ImapClient in C# .NET to easily handle threaded conversations.

C# API for Email Threading Implementation

A simple way to implement Email Threading in your application is using Aspose.Email for .NET. It is a versatile library that empowers developers to efficiently handle emails, including creation, manipulation, parsing, conversion, and management of attachments, calendars, and contacts within their .NET applications. In order to acquire the API, you can download its DLL or install it from NuGet using the following command:

PM> Install-Package Aspose.Email

What is Email Threading?

Email threading is a technique that organizes hierarchically all scattered replies and forwards across your inbox and presents them in a coherent view. This method is especially valuable when dealing with lengthy email exchanges involving multiple participants. The entire process is based on the use of headers to determine the subject and reference relationship and order. The main headers that are used for threading are:

  • Message-ID, an unique identifier for each email message
  • In-Reply-To, the Message-ID of the email that this message is a reply to
  • References, a list of Message-IDs of all the previous messages in the conversation

Building Email Threads

One of the features provided by our powerful Aspose.Email library for creating and manipulating email messages is threading using ImapClient.

ImapClient is a class that allows you to connect to an IMAP server and perform various operations on your mailbox. You can use it to list, fetch, search, move, or delete messages. It also allows to append messages, and build a tree structure that represents a conversation. For example, consider the following email thread:

  • A: Hello, how are you?
  • B: I’m fine, thank you. And you?
  • A: I’m good too. Do you have any plans for the weekend?
  • C: Hi, I’m joining this conversation.
  • B: Welcome, C. We were just talking about the weekend.
  • C: Oh, I see. Well, I’m going to visit my parents.

The tree structure of this thread would look like this:

A
└─B
  ├─A
  └─C
    ├─B
    └─C

Each node in the tree corresponds to a message, and each edge corresponds to a reply. The root node is the first message in the thread, and the leaf nodes are the last messages.

Email Threading Compatability with IMAP

Basically, the IMAP protocol supports the THREAD capability defined in RFC-5256 and understood by most of email servers. But, if you’re working with Gmail, there is another IMAP extension provided by Gmail and described as X-GM-EXT-1.

Aspose.Email has the following properties to check the extensions available for the current IMAP server:

The GetMessageThreads method in ImapClient returns a collection of objects MessageThreadResult, representing information about a message and its relation to other messages in the tree structure.

Get Email Threads using THREAD Capability

The following C# code samples show how to make use of email threading features with THREAD capability of the IMAP server.

using (ImapClient client = new ImapClient("imap.domain.com", 993, "username", "password", SecurityOptions.SSLImplicit))
{
client.SelectFolder(ImapFolderInfo.InBox);
// get a list of messages that we'll group by conversation
var messages = client.ListMessages();
// make sure the IMAP server supports THREAD capability
if (client.ThreadSupported)
{
foreach (var conversationId in messages
// this query just gets unique conversationId for our example
.Select(message => message.ConversationId)
.Where(conversationId => !string.IsNullOrEmpty(conversationId)).Distinct())
{
// create the necessary search conditions for a thread
var conditions = new ThreadSearchConditions
{
Algorithm = client.ThreadAlgorithms[0],
UseUId = true
};
// get results
List<MessageThreadResult> conversation = client.GetMessageThreads(conditions);
// print the email conversation in hierarchically manner
PrintConversaton(string.Empty, conversation, messages);
Console.WriteLine(new string('-', 20));
}
}
}
/// <summary>
/// Prints the email conversation in hierarchically manner
/// </summary>
public static void PrintConversaton(string indent, List<MessageThreadResult> conversation, List<ImapMessageInfo> messages)
{
foreach (var thread in conversation)
{
Console.WriteLine("{0} ({1}) {2}", indent, thread.UniqueId,
messages.Find(x => x.UniqueId == thread.UniqueId).Subject);
if (thread.ChildMessages.Count != 0)
{
PrintConversaton(indent += "-", thread.ChildMessages, messages);
}
}
}
view raw Get-Email-Threads-using-THREAD.cs hosted with ❤ by GitHub

Get Email Threads using X-GM-EXT-1 Extension

The C# code samples below demonstrate how to get the email threads via IMAP from Gmail server.

using (ImapClient client = new ImapClient("imap.gmail.com", 993, "username", "password", SecurityOptions.SSLImplicit))
{
client.SelectFolder(ImapFolderInfo.InBox);
// get a list of messages that we'll group by conversation
var messages = client.ListMessages();
// make sure the IMAP server supports X-GM-EXT-1 extension
if (client.GmExt1Supported)
{
foreach (var conversationId in messages
// this query just gets unique conversationId for our example
.Select(message => message.ConversationId)
.Where(conversationId => !string.IsNullOrEmpty(conversationId)).Distinct())
{
// create the necessary search conditions for a thread
var conditions = new XGMThreadSearchConditions
{
ConversationId = conversationId,
UseUId = true
};
// get results
List<MessageThreadResult> conversation = client.GetMessageThreads(conditions);
// print the email conversation in hierarchically manner
PrintConversaton(string.Empty, conversation, messages);
Console.WriteLine(new string('-', 20));
}
}
}
/// <summary>
/// Prints the email conversation in hierarchically manner
/// </summary>
public static void PrintConversaton(string indent, List<MessageThreadResult> conversation, List<ImapMessageInfo> messages)
{
foreach (var thread in conversation)
{
Console.WriteLine("{0} ({1}) {2}", indent, thread.UniqueId,
messages.Find(x => x.UniqueId == thread.UniqueId).Subject);
if (thread.ChildMessages.Count != 0)
{
PrintConversaton(indent += "-", thread.ChildMessages, messages);
}
}
}
view raw Get-Email-Threads-using-X-GM-EXT-1.cs hosted with ❤ by GitHub

Conclusion

To sum up, now you have an indispensable tool for managing the overflow of your inbox messages efficiently. The article empowered you with the knowledge of the Email Thread benefits, its usage and other useful tips on its implementation. By leveraging the capabilities of the ImapClient in C# .NET, developers can easily implement email threading using the Aspose.Email library. With its comprehensive features and support for various email tasks, Aspose.Email simplifies the process of building email threads, organizing messages hierarchically, and presenting them in a coherent view. Besides, you can explore how to work with several other email file formats and learn more about the API using documentation. In case of any ambiguity, please feel free to contact us on our free support forum.

See Also