Wrong senders listed from LinkedIn Groups and private messages in Outlook inbox

I have been having a very odd problem within Outlook for Mac 2011 for awhile.

I subscribe to multiple LinkedIn Groups and get daily email digests sent to me in batches throughout the day. For each batch of emails, the sender (i.e., Group Name) always ends up the same, regardless of the actual Group it came from and the body of the email showing the correct content from each Group. Somehow one of the Groups that is included in each batch is randomly applied to all Senders/Froms for each email in the batch.

I thought this was limited only to the LinkedIN Groups, but yesterday I received a few private messages as well (for my birthday) a very short time apart, and they all showed up the same from one of the several senders. That has never happened when I only receive a single periodic private LinkedIN message. So, it must be the multiple messages arriving relatively concurrently making the Sender name confused.

I contacted LinkedIn, and their troubleshooting led nowhere and they absolved themselves of responsibility.

I have used Spotlight to see if somehow the LinkedIn Group names are stored somewhere on my Mac, but I can find no trace of them except in previous daily digest emails.

Does anyone have an idea of what might be happening and how to fix it?

Thanks,

Steve