Using IMAP to download mail from a mailbox has the following problems:

  1. IMAP is used to sync folders on the server and desktop clients. If you do an IMAP sync and then delete the contents on the server, you could lose the mail on the client.
  2. For large syncs, the company Internet will get used up leading to slow Internet access for all other users of the company.
  3. Large sync may lead to corruption of data in the email client.
  4. The email client will become unresponsive for the user and regular mail flow will be hampered
  5. Depending on the Internet bandwidth and the size of the mailbox, sync may take many days.
  6. The ISP may block the IMAP port if the download crosses the threshold set.
  7. IMAP access to the account on the SkyConnect server will get blocked if it crosses the threshold.
  8. May cross the size limits of a PST in the desktop client.