When using the Exchange Connector and users reply to the mail, including the [SRxxxxx], if not configured correctly, the connector will create new activities, even despite the SR being completed.

If the Exchange connector is set to use the Default Service Request when updating Service Requests, these two new activities will be added every time to user replies to a mail.

To workaround this you need to create a SR template that doesn't contain any activities:

After creating the SR Template, configure the Exchange connector use the new template:

When a user replies now, the End-User comment is added but no status change nor are more activities added:

As an SR can't change status to 'Updated By User' like Incidents, several of my customers manually monitor the mailbox for any replies to a Service Request and handle this on a case by case.