Trying to access D2L email through Outlook 2019 Good morning, I'm potentially snipe-hunting, but...

Trying to access D2L email through Outlook 2019
Good morning, I'm potentially snipe-hunting, but I'm trying to access the email server within D2L Brightspace using my desktop version of Outlook 2019. I'm told the system is currently set to operate on an internal basis only, which may be a physical hardwire limitation or a "we just don't do that".
In practice, students can send me email to my D2L address and I can send them email to their D2L address all through the web portal in D2L. However, If I try to send an email to a D2L address from the outside (say, my regular school account), the student doesn't receive it and I don't get a bounceback. So while I could (and have tried to) forward email to my school account, replying from my school account just has things vanish into the abyss...
In a perfect world, I'd like to be able to configure an email account in Outlook for my D2L emails. My computer logs in (using the appropriate IMAP/POP3/etc settings) and downloads the email(s) from students. Then, since I have the login credentials, I can send emails back out to the student D2L accounts because we're all part of the same happy system.
It would be even better if there were a way to add headers to the email subject line so that it's sortable by course , but that's just being greedy...
Anybody have an idea how to accomplish this, or know of the question phrasing I should put to IT? I've long since learned it's not always what you're asking for, but how you're asking that makes the difference.
Thanks!
Gordon