When Outlook 2013 is opened on desktop and a Security Alert for a certificate issue is displayed:

 

Solution:

  1. Close Outlook 2013
  2. On your desktop, go to START > in the search bar type CMD
  3. In the command line, type ipconfig /flushdns
    1. When it has completed, type exit
  4. Open Outlook 2013
    1. You will see the same Security Alert, but it will be the last time
    2. Click Yes and/or Allow for any windows that pop up
    3. Close Outlook and reopen it one more time to make sure the Security Alert does not show.
      1. If the Security Alert shows again, proceed to step 6.
  5. Finished
  6. Close Outlook 2013
  7. On your desktop, go to START > Control Panel > Mail > Show Profiles…
  8. Select and Remove any profiles in the box except "Outlook"
  9. Click Add…
  10. Enter a profile name for your corporate email account > Ok
  11. The system will auto recognize your AceInfo email information. If not, manually enter it > Next
  12. Click Yes/Allow to any windows that pop up
  13. Enter your email password if/when prompted, fill in the "Remember my Password" box > Finish
  14. Open Outlook 2013 and sign in, you will have no more issues but your inboxes will take some time to reload.