Outlook Anywhere via rackspace.com doesn't work.
Outlook RPC over HTTPS to Exchange server not working.
Some SSL server host prevents or drops the connection if it detects there is a middle man (intercept) the stream, sites who has this restriction is usually enforced its confidentiality like banking, finance etc.
Bypass this stream of SSL traffic:
1.) Login to the portal (portal.threatpulse.com).
2.) Select Service > Network > SSL > Pass Through Domain/URL.
3.) Add the connecting server resolved IP address: 188.8.131.52.
4.) Click Activate.