Why do emails thread to the wrong ticket?

Question

An email message threads into an existing ticket as a comment instead of generating a new ticket. Why do emails thread to the wrong ticket?

Answer

When a new email is received, Zendesk scans the message-ID on the email. If that message-ID matches an existing ticket then the email is added as a comment on the existing ticket. Zendesk does this regardless of the support address the email is received at.

The threading logic from an email is based on RFC standards. All of the lines for In-Reply-To and References should contain unique values. If one of these lines uses a static message-ID or email address, Zendesk will thread incoming emails into the same ticket.

Make sure that you are not removing all of the text from another email conversation and resending the email or just changing the Reply-To address. To create separate tickets, copy the email content into a new email and manually send it to your support address.

Note: The available threading header data is kept for 30 days. If an email response to an existing email thread is older than 30 days, the data won't be available to make a thread connection. 

Checking your original email

To determine what is causing your tickets to automatically thread multiple emails into one single ticket, follow the steps below to examine the original email records for matching message-IDs.

1. Open the original message that began the ticket. A window or a new browser tab will show you the original data from the email that was sent to Zendesk.
2. Repeat this for the next threaded message that comes from the same sender that should be a separate ticket.
3. Select Source for both of the messages under the subject line. This will display the header data.

Analyzing the header information

The data in the Source tab covers a large amount of data that is hidden by email programs. The critical information is listed as one or more of the following items:

• Message-ID:
• In-Reply-To:
• References:

If you find Message-ID within the headers of the email, this is the first email written as an original message in this format. Copy the string found next to message-ID, and check the References entries for matching messages. Use the Find function (Control-F or Command-F) by pasting the string.

If you find In-Reply-To or References, this shows the message is a reply to a pre-existing message in the requester's email account. Use the Find function to check for more Reference strings to check for matches. This will confirm that the requester replied to saved messages in their inbox instead of submitting a new separate request. You are likely to see this if the ticket in your system is listed as a follow-up ticket.

Finally, another reason might be that the encoded ID from another ticket, which is used for threading incoming email replies into existing tickets, appears in the email.

For more information, see the article: Understanding How Incoming Emails are Matched to Tickets