I have been struggling with persistent errors with Outlook for Mac for months and I am just fed up with it. After having re-archived all my mail and re-built my local Outlook calendar (cleared the cache and downloaded last data from Exchange server) yesterday, I am still being plagued with error messages. Examples as follows:
Error code 17886. Error: An unknown error has occurred in Outlook. Details: Mail could not be sent.
Error code 18000. Error: While downloading the meeting It's Breakfast Time!, some attachments may have been lost. Details: To try to recover the attachments, hold down CONTROL, click the calendar in the Navigation Pane, and then click Folder Properties. Then empty the cache. Outlook will then download the latest version of the meeting to your calendar. Open the event again. (This is precisely what I did yesterday and it took 10+ hours for everything to sync!)
Error code 19995. Error: Permission Error. The folder "" could not be moved or deleted because you do not have the appropriate permission on the server. Details [none]
Error code 19707. Error: Could not synchronize record: Work From Home today to Exchange server: Esecuritel. Details: The request timed out.
If anyone can provide any input to the root cause here - local Outlook installation or Exchange server; or can provide specific help on one of the examples provided that would be fantastic.