TL;DR My organization is running on-prem Dynamics GP 2018 and is trying to send out automated remittance emails when processing batches. I was able to get this to work several months ago, but after updating our instance of GP to 18.6, the integration no longer works. After the user logs into the MFA app, no mail gets sent.
The integration is set up to use an app registration in Azure AD/Entra to let the user's account access Exchange using MFA. This app uses Graph to access the user's mailbox and send mail. GP connects to this app after I enter the app I.D. into the /Company E-mail Setup/ window, then log into Entra with my admin account.
When a batch is processed and GP tries to send email, the user is prompted to log into the cloud. Since the user is already logged into a virtual desktop using an Azure-linked account, they usually just click their username to progress:
After this, the email should go out. However, it never does. It's not a mail delivery issue, since it's not even leaving the user's mailbox. It's not Azure either, since there's no error after logging into the user account.
These are the guides I consulted when setting it up in June of last year:
I have attempted the following while troubleshooting this issue:
If anyone has any ideas, I'm all ears. I'm not sure what else to try.