I keep receiving other peoples emails on my live.co..uk email address, some of them have confidential information . It looks like there is a security problem on outlook.com or they have issued duplicate email addresses

Has anyone else seen this and is there a way to get this problem fixed.

I use the Microsoft + SEVEN outlook app to vissit Outlook on my android tablet. However, to install the app I had to accept a permission: Permission to read callendar events plus confidential information. I'd liked to know two things about this permission. 1. What exactly is meant with "confidential information". And 2. How does microsoft store and use this information?
I was prompted to download a 2011 Microsoft Office update for my mac OS X 10.6.5. After the download a popup box appeared, saying, "Microsoft Outlook wants to use your confidential information stored in pop-server...etc...in your keychain" with the options of "Always Allow, Deny and Allow". I checked "Deny"; however, Microsoft won't take "no" for an answer and the same prompt continues to reappear incessantly though I continue to answer "Deny". It's annoying, intrusive and I want it to stop.
This message started arriving yesterday when I downloaded an update for Outlook for Mac 2011. I have to choose "deny" or "allow". I choose allow because I can't receive my email otherwise. Once allowed it reloads 6-8 times, always with the same sentence as above.. Is this a screw up in the update?

Thanks
I continuously get:
outlook wants to use your confidential information stored in "InternetAccounts Access Group" in your keychain

each time my Outlook tries to get email messages.  I have responded to always allow, but that does not cure the problem.  I have also gone into the keychain list and tried to allow ALL applications to access this itme to NO avail.  What to do next???