Working on Exchange/Outlook 2010 I understand conversations should be linked by "conversation index" despite of the "subject" line to be changed during the "conversation"... is that correct?

In my case "conversations" appear to be grouped by "subject" which means, any change to the "subject" during a reply is starting a new conversation.

Environment:
Exchange version: 14.3.235.4001 which I understand is Exchange 2010
Outlook version: 2010

Is this a known issue?
Am I doing something wrong?
Is it there a step-by-step guide to get this working? meaning, conversations grouped by "conversation index" rather than "subject"?

Any and all help would be much appreciated.

PB

• Edited by PaulB_new Thursday, July 23, 2015 6:08 AM Typo

Thank you for the detailed answer Steve.

I remember reading in some place - it this forum - that "conversation id" should not change when subject line changes; is that an improvement in some particular version of Outlook beyond 2010?

Thank you in advance,
Paul