Receive Email step and Exchange on Prem

Hello guys,

We’re facing a situation where our client is using Exchange on-premises, and they’ve informed us that they’re utilizing port 443 for receiving emails. However, SMTP, POP3, and IMAP are disabled.

Upon testing with the telnet command on port 443, we found that the port is open. Additionally, we discovered a way to access the mailbox through the URL: https://mail.clientname.rs/api/v2.0/me/message.

Our understanding is that the client should provide us with access tokens, such as client ID and secret, to enable us to call the API through Azure. However, they’ve declined to create access tokens, citing their on-premises setup.

Instead, they suggest “impersonating” Outlook by providing server, port, username, and password for email retrieval in the background.

We’re uncertain about our capability to perform this impersonation. Could anyone provide guidance or insights based on similar experiences?