I can honestly say that after this week, I would never recommend anyone buy Office 365 for their corporate email solution. Last week Microsoft "upgraded" Office 365 to the new 2013 look/feel. In so doing they've changed all the DNS settings (requiring our corporate DNS settings to change and innumerable headaches on my part fixing all the Outlook 2007 installs.)
Secondly, Microsoft removed the spell check from their Office 365 product on the basis that "modern browsers all have built-in spell check." They seem not to understand that Office 365 users are mostly corporate email clients, and may not enable all the features of, or the access to modern browsers for their users.
Some jerk replied to my note of this on the Office 365 support/discussion forums that this was akin to asking Ford to put a handle back into cars to roll down the window, as if we somehow don't need spell checking any more? Really?
Keep in mind that Microsoft INCLUDED spell check in their new email product "Outlook.com".
Do yourself a favor, look into Google's corporate offerings. Just check out the other posts on Office 365 I've posted and see if you want to live through it.