DirectAdmin Office 365 hybrid configuration

[marcel.brabetz]

Hello everybody,
I'm totally new to this forum and Directadmin itself. We were asked to setup some kind of hybrid mailbox configuration with Office 365 environment.
The aim is to host mailboxes for one maildomain of some users in Office 365 and some in Directadmin itself.
Actual setup:
The Directadmin on CentOs is handling mailboxes, mx and dns on it's own. DKIM and SPF is published.

My question: is it possible to configure Directadmin to support one of this 2 scenarios (i personally prefer scenario 2)?
scenario 1:
- MX records pointing to Office 365 environment, domain hosted as "internal relay domain"
- "power user" mailboxes hosted in Office 365
- SMTP send connector in Office 365 pointing to DirectAdmin server for all "normal user" mailboxes that aren't hosted in Office365 to enable mailrouting towards DA
- DA accepting this incoming mails for the same domain
- Outgoing mails from "normal users" towards "power users" should be send by SMTP using MX records or a special SMTP connector into the Office365 environment to enable some kind of internal domain mail routing

Scenario 2:
- MX records pointing to DirectAdmin environment, domain hosted on Directadmin and Office365
- "power user" mailaddresses having direct forwarders (aliases) towards the corresponding mailbox "[email protected]" hosted in Office 365
- SMTP send connector in Office 365 pointing to DirectAdmin server for all "normal user" mailboxes that aren't hosted in Office365 to enable mailrouting towards DA
- DA accepting this incoming mails for the same domain
-

I know i have to adjust SPF entry to avoid false classification of outgoing mails.

I hope i have described my aim in a proper way.
Would be great if someone is sharing his thoughts on this and can give hints to me.

kind regards from Berlin
Marcel