We have 10 W7 PC's connecting to an outside Exchange server, 6 of them are using Outlook 2010 and are functioning like you expect, 4 of them are using Outlook 2007 and keep asking for a server password. That password is stored in the references, but for some reason it is not used or not working next time. I noticed that Outlook 2010 is using different references from 2007, but adding the 2010 references in a 2007 PC does not help. I have found on internet a variety of solutions, also from Microsoft, none of them helped, see: - Password not remembered in Outlook 2007 or Outlook 2010 on Windows Vista or Windows 7 - MSOutlook.info - https://support.microsoft.com/nl-nl/kb/290684?p=1 Those 6 Outlook 2010's which are working make me believe that it is an Outlook 2007 problem and not a fault in the exchange server neither a problem with some security setting. Anyone an idea?