I can't see any way of modifying the date categories in Outlook's email item list.

I personally find the existing, default categories of "today", "yesterday" followed, one by one, by the remaining preceding days of the week, all a bit unnecessary; though maybe I wouldn't if I had vast amounts of email coming and going.

Conversely, I find having just "This year" and "Older" for everything else far too little.

If only it could be personalized, in my case to commence with "This month", "This year", "Last year" and then, one by one, all of the relevant years before. And it surely couldn't be too difficult for the obliging Microsoft programmer to have everything before "Last year" self-update so as to always read as the year in question; eg, for the year before "Last year" to currently read as "2012", etc.