OUTLOOK – SENDING INCREDIBLY SLOW OVER IMAP

Could be the Get folder unread option:-

  1. Go to “File -> Options”
  2. Select “Advanced”
  3. Click the “Send/Receive…” button under the “Send and receive” section
  4. Select the “All Accounts” group and click the “Edit…” button
  5. Uncheck “Get folder unread count for subscribed folders”

Optionally:-

  1. Select “Use the custom behavior defined below” option are under “Receive mail items”
  2. In the “Select folders from the selected account to include in send/receive” box, check any folders that automatically receive mail. This would include inbox and any others folders that may have content filters that automatically deliver new messages to them.
  3. Close Outlook and re-open
  4. Mail should now send and receive.