What is email threading?

Email threading is the technique that groups this chain of messages to one "thread," giving users an organized view of each email conversation. As our reliance on email continues to grow, with more than 347 billion emails sent and received daily in 2023, email threading has become increasingly important in crucial business communications. It allows teams and end users to seamlessly track emails, keep stakeholders informed, and reduce email inbox clutter.

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What is an email thread?

An email thread is an email conversation that starts with one message and includes all replies and forwards connected to that message. It is essentially a conversation history for your email and consists of one long email conversation containing all correspondence related to the original email. Rather than displaying each email individually, email threads make it easy to follow a conversation, view past messages, and understand the context without having to search through your inbox. 

Step-by-step: how does email threading work?

An email threading feature analyzes and identifies elements of an email, looking for connections between them, and then groups the emails together into a continuous thread. Here is how it works: 

Step 1: First, a text analytics algorithm in the email threading functionality examines a data set and identifies segments — parts of the conversation — within the data set. The algorithm compares the segments, looking for similarities that indicate they belong to the same conversation. 

Step 2: The email threading algorithm next determines which type of communication exists in the embedded messages inside the emails, such as whether each is a reply, a reply-all, or a forward. 

Step 3: The email threading functionality then correlates and groups the emails and attachments. When the algorithm matches the segments, it groups the emails and attachments into a neat thread, called a thread group. 

Step 4: The algorithm then analyzes variables in the thread group. The email threading functionality will analyze and normalize the header data, including dates, senders, and recipients in the original email and subsequent messages, as well as sent time, attachments, and email text, to determine if the emails are inclusive (they contain all the text and attachments) or non-inclusive (a single reply or the last message in a thread). 

Benefits of email threading for end users 

Adding an email threading capability to your application provides many benefits for users and product teams. Of course, for both, there are some considerations to be aware of. Let’s take a closer look:

Keeps all recipients informed 

By grouping all emails related to the original one, all recipients are in the same loop. This feature then enhances communication, especially for business and commercial applications. For instance, customer service apps may benefit from email threading by keeping all communications related to one customer’s ticket in the same place. Customer service agents can see a holistic view of a customer’s conversation, enabling them to reply or resolve issues with accuracy and efficiency. 

Enhances the user experience 

Simplified email threading helps end users understand the key messages in the thread, so it’s easy to follow the conversation. This can be a valuable feature for technical support teams in an application, as it allows agents and users to follow the entire ticket process in a single place. 

Reduces inbox clutter 

Email threads simplify inbox management by keeping all the connected messages in one place. Users can scan through a thread and find the information they need without having to scour the entire mailbox, as well as search and filter emails by keyword. Email threading reduces email duplication and saves users from having multiple emails related to the same subject. 

Email threading considerations for users

Some recipients may get irrelevant emails

Not all the emails in a thread may be relevant to all the recipients. In a long thread, some emails may be relevant only to a portion of the recipients. 

Emails can get convoluted 

Some threads can get too long and convoluted to be followed easily by users. Also, if users delete an email in the thread, it can delete other emails that may be important. 

Benefits of email threading for product teams

Simplifies e-discovery 

E-discovery is a type of digital investigation that attempts to find evidence in emails to use in criminal or legal processes. The evidence may include data from instant messages, email accounts, and other online documents. Email threading is an essential tool for e-discovery, as it can provide key information in cases of data breaches. 

Emails can have dozens or hundreds of segments, some of which are important for an investigation and many of which may be irrelevant. Reviewers benefit from email threading because it allows them to see the inclusive messages and get the whole conversation in one place. 

Simplifies email analytics 

Email threading detects and correlates the relationship between emails, normalizing email metadata. This feature simplifies email analytics, such as for security purposes. 

Saves developers time and resources

Integrating an email threading API reduces most of the building work by giving a single, integrated solution. The development time and resources needed decrease dramatically. 

Email threading consideration for product teams

Email threading is not universally supported

Some email providers — such as Gmail and Outlook — don’t support email threading, so the options for setup in an app can be limited. 

Email threading in an application

Incorporating email threading into an app can be extremely useful for end users, as it reduces confusion in the inbox, preventing users from sifting through countless emails and enhancing your app’s user experience. 

Despite how useful email threading features are, implementing them in widely known email clients can be cumbersome and time-consuming. To add email client functionality to your application, you need to configure the settings and options for each client, such as how to group the threads, which messages to show and which to hide, and how to mark the threads. All these require considerable time and effort. 

A simpler alternative is using an email API like Nylas that supports multiple integrations. Nylas simplifies email threading across clients, so you don’t need to set them up individually. Nylas integrates with every email provider including Gmail, Microsoft Exchange, MS Office365, Microsoft Graph, Outlook, iCloud, and IMAP. Check out the complete list of supported email providers with Nylas.

Challenges of email threads

As the number of emails generated and received by the average company grows, it becomes increasingly difficult to manage email threading. To compound the problem, emails usually don’t have metadata identifying them as part of a specific thread, so it’s up to the email client to determine how to group emails and display the threads. 

How the thread is displayed depends on the user interface of the email client, which may cause display issues. Therefore, building an email threading feature in an application with email capabilities can be time- and resource-consuming. 

Email threading with an email API 

Developers integrating email capabilities into an application aim to provide a consistent and easy-to-understand view of email conversations. An API solution can simplify email threading by establishing which messages belong to which threads. Deleting and archiving messages can also be done individually or as part of a thread.

The Nylas Email API integrates with the user’s inbox, providing bi-directional email. Building a threaded email inbox view will help your users access their email data from within the application.  

If you are a developer thinking about integrating email functionality into your app, read on to learn more about email threading, its benefits, and its challenges. Want to learn more about the value of threading in an email API? Check out this post.

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Simplify your email threading with Nylas

No more convoluted and difficult-to-group threads. The Nylas Email API takes care of this complexity by offering an all-in-one solution that simplifies email threading and connects all email, calendar, and contact service providers with your application. It uses REST APIs to take the hassle out of building email threading algorithms, allowing you to deploy your engineering resources towards other critical work. 

Discover how the Nylas Email API makes it easier to build a threaded email inbox. Request your free API key and start building. 

Frequently asked questions

What is a threaded message?

A threaded message is a message within a thread. Messages before any replies are called “unthreaded messages,” and the message that gives origin to the thread is called a “parent“ message. The replies are also called “child messages.” 

How does email threading handle unsupported header languages?

Typically, when headers are in unsupported languages, the groups of emails in a thread are split into multiple threads according to the language used. 

How do email clients track conversation threads?

Email clients match in-reply-to and message-ID headers to identify which thread corresponds to what email. 

What’s the role of email threading in email security?

Email threading is essential for email security processes, such as review and forensic analysis. An email thread groups all connected documents from an email conversation, including attachments. This simplifies the reviewer’s task by identifying inconsistencies or discrepancies.  

What are indentation levels and their role in the email threading ID?

Messages inside a thread are assigned an order number and an indentation level that goes both in the document and in the visualization field. The indentation aims to create a visual separation between the different email segments. 

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Additional Resources

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