No email date range limit in 10.1 - carful what you wish for :-)
I have been one that has wanted to see the 30 day limit go away. I am on BES and setttings were set to unlimited by admin but as many know this has no impact on what the device will bring down. Was always bringing 30 day rolling window. Well 10.1 leak has taken it to the opposite and I am now finding that I had mail in my inbox and sent back to 2008! Clean up into archive before you go to these settings!
I am slowly cleaning up on both sides rather than re-doing my enterprise activation but it does seem to be having trouble with this much mail. I don't expect it to deal with this much as outlook itself struggles.
Also finding that "delete prior" won't do large volumes at a time. Best it wants to do is a couple days at a time. (100 a day). On 7 you could kill huge amounts in groups.