Thanks for your post.
Please could you tell whether your exchange server supporting Pop3 or Imap accessing. In order to access the mail box in exchange server, we can use the Pop3 component or Imap component to retrieve the emails. For example, you can active the Pop3 or Imap service in the exchange serve, then use the Pop3 or Imap component to get the files.
With Pop3 protocol to access exchange server, you can only visit the inbox folder, while the Imap protocol will allow you fully access to the other folders in the mailbox.
Aspose.Network support Pop3 and Imap protocols.
Feel free to access me with any problems.