First confirm that the URL used by Outlook to connect the Exchange Server is accurate like the same it was on Entourage.Reset password through Outlook Web Access (OWA) and re-execute Entourage to fix the error. You may also receive Error 18597 when password entered in user’s active directory account has expired.Because of the mismatching of the email address, Outlook 2011 does let it to connect with Exchange Server. This error may appear when the email address is typed in the dialog box of Exchange account doesn’t equivalent with the one the Exchange Server expects.This error is called Error Code 18597 on the Mac system. In some cases user may receive error message while attempting to connect Outlook with the Exchange server to open mails, messages, calendars etc. At this time you will get a list of messages but the downloading process installs only when user views every single message. Navigate to Outlook Menu > Preferences > Accounts > Choose the Exchange account > Go to Advanced Tab > Choose Download Headers only option. In order to get “online mode” in Outlook for Mac apply the below given method: Mac Outlook 2011 is always executed in cached mode unlike Outlook for Windows.
