How email threading works

Updated Nov 9, 2026

When a customer replies to one of your emails, the reply is added to the same ticket instead of creating a new one.

How a reply finds its ticket

ChaosDesk checks these signals, strongest first:

A signed reply address. Replies go to an address like support+id…@ that carries the ticket number and a signature, so nobody can guess it to post into another ticket.
The email headers (In-Reply-To and References) that point to a message ChaosDesk sent or received.
A signed ticket reference in the subject or body.
The ticket number in the subject, such as [#1234], but only if the sender is already on that ticket.
A reply ("Re: …") whose subject matches one of the sender's open tickets updated in the last 14 days.

If nothing matches, the email becomes a new ticket.

Replies to closed tickets

A reply to a closed ticket creates a follow-up ticket linked to the closed one, tagged follow_up. The closed ticket stays as it was.

Quoted text

ChaosDesk keeps only the new part of a reply. It removes:

everything below the ##- Please type your reply above this line -## line;
quoted history from common mail apps (Gmail, Outlook, Apple Mail, Yahoo, Thunderbird) and "On … wrote:" lines in several languages;
trailing > quote blocks;
a trailing phone footer such as "Sent from my iPhone".

The full original email is kept. Use Show original on the comment to see it.

CCs

People in To or Cc of an incoming email are added to the ticket as CCs, up to 48 per ticket. Two settings under Admin Center, Channels, Brands & email, Email settings control this:

End users can add CCs by email: when off, only agents' CCs are kept.
Agents CC'd by email also become followers.

Loops and automatic mail

Mail from your own support addresses is dropped, because it would loop. Bounces never create tickets. Auto-replies, bulk mail and mailing lists go to Suspended tickets.

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