Office 365/2016 or 365 business versions include the use/ability to use exchange but MS does not supply the actual exchange account
Depending on your domain provider you can redirect the DNS to entries to point to an onmicrosoft.com account (exchange)
Set all the required DNS entries at your current provider except for the MX records.
The SPF record can often be safely omitted during testing, but if you want to set them, make sure you allow both the outlook.com servers as the servers from your ISP.
Associate your own address (or your testing address) with the Exchange Online account and set it as the default for the mailbox
In the admin portal of your current provider, set a forwarder on your mailbox to the @accountname.onmicrosoft.com address. Make sure that it will also still deliver to your
mailbox on that ISP.
You can basically run like this indefinitely. Even when you want to stop using your POP3 account and want to take the Exchange Online account into production. You can opt
to stop delivering it to your POP3 mailbox and only forward it to the onmicrosoft.com address or to keep delivering it to both and clean out the POP3 account every now and then.
This configuration also allows you to only host a couple of mailboxes for your domain on Office 365 while others remain POP3. In this setup, you must however set your domain
as an Internal relay domain on Office 365. You can do this in the Exchange admin center-> Mail flow-> Accepted domains
Ref:
Robert Sparnaaij [MVP-Outlook]
http://www.howto-outlook.com