Setup IMAP / SMTP for Outlook 365 in Intune

Hey folks,

right now we are trying out the possibilities that Intune gives us and I'm trying to eleminate any hands on work on the workstations themselves. And it seems like I already found the first showstopper:
We are using an external mailserver (IMAP / SMTP with customs port config) and are not allowed to use Exchanges services (stupid - I know, please let's not discuss this fact. I'm working in the public sector and here the clocks tick a little bit slower).
That means I need a way to preconfigure the Outlook client on the workstations so the user will only have to enter his credentials in the best case.

I already ran over some useful topics like autodiscover DNS settings and other things, but the main problem is that Outlook will try to setup the mailbox over Exchange and - as if we don't have enough other problems - this will work, because there is an Exchange service running.

TLTR:
- Is there a way to configure a mailbox in Outlook that uses IMAP/SMTP over Intune?

- If not -> do you have any other ideas?

Thanx in advance for your help. As mentioned before - I know that we are running a suboptimal infrastructure. Please let's not discuss that part! It's frustrating enough for me and the rest of our team. 😉