On June 29 a power blackout shut down the computer (iMac i7 OSX 6.8). The next day I found the entire Outlook contents of all emails was missing.

On June 30 I went through the process of restoring the identity (which I had had to do several times before). I used the latest identity, November 20 2014, the last time I had been forced to rebuild the emails database.

The operation restored almost all emails, but none of those between November 2014 and June 30 2015. There is no reason for those emails to be selected or treated any differently from the rest which go back to 2006.

I tried several more times but could not recover those six months of emails. My ISP could not provide them from its bankups.

Finally yesterday, with the help of my son, I tried to solve the problem using Time Machine. I went back to June 27 and followed the steps to restore the identity and emails on the system at that time.

The operation went according to the suggested steps, except that renaming the Main Identity on the Desktop to "Restored Main Identity" had no apparent effect, because when dragged to the Documents>MS User Data>Office 2011 folder, it immediately changed its name to Main Identity.

When I opened Outlook I was delighted to find the email Inbox complete. Scrolling back, there were all the emails for June, May, April, March. Suddenly after less than a minute since opening Outlook all those six months of emails DISAPPEARED. I would not believe it except there were two witnesses looking over my shoulder.

Subsequent attempts to go back in Time Machine to restore Outlook only produced the same result - six months of emails missing.

It would seem that Outlook defaulted to the Identity as restored on June 30 - that is missing the six months. 

It is clear that the six months of emails are still on my system, and can be accessed via Time Machine. What is not clear is what happened and why the full email database was not stabilised when it was restored.

This is just about the last straw in having to deal with this unstable, unreliable and frankly dangerous program. I'd be grateful if some of the community leaders could diagnose the problem and show me a way out of the mess.