Re: How would Office 365 work if we didn't want email at all?

Hi Luke,

In Office 365, we have three mail services: Exchange Online, Lync Online and SharePoint Online. Customers can choose to use one/all of them. Since members In your organization have their own email solutions, they can choose not to use Exchange Online. You need to assign the corresponding license to each user.

If a user doesn’t include Exchange Online license, it is not available for him to use calendar and other features included in Exchange Online.

In addition, here is an article about assigning license, please refer to it to get more information: http://office.microsoft.com/en-us/office365-suite-help/assign-or-remove-licenses-or-view-a-list-of-unlicensed-users-HA102816053.aspx?CTT=1

Please feel free to let me know if you have any questions.

Thanks,
Nate Cui