Replies on the same email thread (with same subject) after it is un-tracked, still getting tracked into CRM.

here is the scenario:
1. There is an email that is tracked using Dynamics 365 App for Outlook which is Sent to a customer.
This creates the email activity in Dynamics 365 as expected.
2. The customer Replies to this email and the email is picked up by SSS Automatically which creates the Email Activity Record in Dynamics 365.
This is working as expected.
3. You then use the D365 App for Outlook to Untrack the most recent email which removes the email activity that was created in the step above.
This is working as expected.
4. You reply to the email which you have untracked using the D365 App for Outlook. When the customer replies to this email, the email is picked up by SSS automatically and promoted to Dynamics 365 which creates the email activity record.
This is not working as expected.