same issue here, please anyone has can assist. or any update for this case ?

^{Service Desk creates a new issue instead of comment to existing issue for original email replied to by request participant.}

This happening again sporadically as per below screenshot - only in the last 3 days 

eric1213677426 check if you are not having the issue tracked in JSD-2373 instead. If that's not the case, open a support ticket in support.atlassian.com .

I'm seeing exactly this issue in my recently created JIRA Service Desk Cloud which is troubling since this issue, and -JSD-2334-, are both reported to be 'Done'.  I'm not seeing any particular setting that I need to toggle.

Any thoughts about why I would still be seeing this?

Hello,

This problem in JIRA Service Desk Server is being tracked in JSD-4320. Please follow that bug for updates.

If you are experiencing this issue in server please vote or comment JSD-4320 so we have your feedback properly tracked.

Cheers!
Tim | Atlassian

thx for the comment (Chris Robinson) I have the same issue with my server instance

This is also an issue on server instances. When will this fix be released for the server edition?

mikkel324661434 The scenario you described above is different from this. https://jira.atlassian.com/browse/JSD-2373 would be the right place to watch for update.

Please be also aware of: JSD-2373

Summary

When a customer of a JIRA Service Desk sends an E-mail from Service Desk to another person (who is not an agent, reporter or request participant) of the issue, if that additional party replies to the issue and includes the JIRA Service Desk E-mail, the E-mail is treated as a new issue, even though:

• Subject Line contains the Issue Key,
• Email Headers are still intact.

For Example:

1. Customer 1 raises a Service Desk request.
2. Agent 1 responds to the Service Desk Request.
3. Customer 1 receives a response and CC's the response to another Customer (Customer 2).
4. Customer 2 responds to the service desk request, CCing in the same people.

Creating new E-mails under this scenario causes additional overhead for the Service Desk Administrator, and may be confusing to the customer interacting with the Agent, due to the fragmented nature of the E-mail interactions

This was introduced as a result of the changes in: JSD-1876 which fixed an issue when a user who was not a Service Desk customer responded to a Service Desk Email.

sohil1563523276 please log a ticket in support.atlassian.com for this.

Cheers,
Dario