Resolving Messenger Sign-in Error 80072ef3

Are you using Windows Live Messenger in a corporate intranet, and experiencing the error code 80072ef3 when trying to sign in? Changed port configurations in Messenger 2009 cause this error to happen, and you will have to bypass your corporate proxy for the Messenger servers.

When you delete or block a contact person, Messenger will try to synchronize your local contact list with the server, and this connection cannot be established properly on some organizational environments.

• Solution 1: Add Messenger servers to exception list
  1. Click Start, Control Panel, Internet options.
  2. Switch to the Zones tab.
  3. Mark the entry Trusted sites, and click the Sites… button.
  4. Add the following entry to the list of trusted sites:
     https://*.contacts.msn.com
  5. Click OK, and switch to the Connections tab.
  6. Click the LAN settings button. If the Advanced button is active, click it and add *.contacts.msn.com to the Exceptions list.
  7. Click OK to close the dialogs.
  8. Retry to sign in to Messenger.
• Solution 2: Choose a different place where to synchronize your contact list
  1. Take your notebook home and connect to your private Internet.
  2. Sign in to Windows Live Messenger.
  3. It will synchronize the contact lists.
  4. Now, Messenger will also sign in at your corporate intranet, as long as you do not change your contact people.
• Solution 3: Switch back to Messenger 2008
  • The last resort is to uninstall Messenger 2009 and start using Messenger 2008 (8.5) again.
    Update 15 September 2009: Since Messenger 2008 does not work anymore, you will have to contact the Messenger support (see below).

If you have a different strategy how to fix this error, please comment on this post. You might also want to contact the Windows Live support at http://support.live.com/.