Major changes to the data file - a lot of changes, could be edits, deletions, new mail. Do you sync with a smart phone or other device? That could trick the search engine into seeing changes that don't exist. Is just outlook re0indexing or the entire computer? If the computer is re0indexing, something could be corrupting the index.
I do get a good number of emails (hundreds per day), but I wouldn't consider it extreme. I do have a couple of items that may be relevant here. I use Crashplan to backup my system. I do see my PST file for my personal POP3 account being read by the "shadowfilecopy" (?) service. I exclude my OST file for my Exchange account from backups.
I also use a tool called CompanionLink Professional to sync my calendars and contacts to Gmail accounts to subsequently sync Gmail <-> Android phone. But I don't sync directly from my laptop to my phone.
I can't tell if the entire computer is re-indexing or just Outlook. I do know that when I check in Outlook: Search Tools | Indexing Status ..., that's where I notice it indexing upwards of 300,000 items.
The other issue which would mitigate the problem somewhat is that when I do see Outlook reindexing, it will take 2 or 3 DAYS to index everything, even if I leave the computer on with nothing else running. It seems to index maybe 10,000 items per hour, which adds up when you're indexing 300,000 items. Any way to speed up the reindexing?
So I guess I have two questions:
First, how can I determine what is triggering the reindexing?; and
Second, when reindexing does occur, how can I speed it up?