Exchange 2007 issues with users logging into outlook using rpc over http (outlook anywhere). Keeps prompting for their password and never connections.
This is because IIS RPC directory has Windows Authentication disabled. Re-enabling it only stays that way for about 5 minutes, then goes back to disabled. This is because of Exchange’s maintenance. The solution is to set basic and ntlm as authentication in Outlook-Anywhere through the Exchange Shell as explained in this guide.
RPC Exchange Proxy – Outlook Anywhere prompting for password and never connects.