Fortimail relay to more than one server at a time?

Hello,

We currently have a Fortimail that forwards all incoming mail that passes spam check to an on premises Zimbra mail server. We're looking at the possibility of migrating to Office 365. My questions is, would it be possible to use FortiMail to forward most of my accounts to @mydomain.com addresses on my main mail server while other addresses that have been migrated to O365 get forwarded to O365? And if so, how to do this? Thanks.