Ok so I am in the planning stages of moving from ex2010 to ex2013.  I also need to renew my MS Volume licenses by the end of the year and figured I should look at O365 as an alternative to hosting this ourselves.  We use Exchange for our corporate email with about 250 mailboxes.  We have about 100 employees that also have access to shared mailboxes so that is why we have more boxes than employees.  We also use items in Exchange like resource booking for conference rooms and vehicles.  We use Exchange Active Sync and OWA for remote users.  What doesn't translate over in to O365 that is in an OnPremise Exchange solution?  AS far as price we our a Non-Profit so we get charity licensing from MS but still it looks like that coupled with Office it might be more cost effective to switch.  Any links to research already done or advice would be great.  Thanks.  

Hi,

Take a look at the limitations here:

http://www.usf.edu/it/services/office365/benefits-limitations.aspx

https://technet.microsoft.com/en-gb/library/exchange-online-limits.aspx?f=255&MSPPError=-2147217396

Notable limitations include message size limits, lack of backup. There is also the option to run a hybrid solution with some mailboxes on premise and some on O365. Companies often do this when they are testing and evaluating O365.

Thanks.