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Here is my situation. Our office just got sold and we are working on the migration to the new company's environment. Everything has worked fine until the Outlook client's migration.

Our firewall is TMG Forefront 2010 and we were all connected using Office 365. The Outlook setup was really simple, as we used the autodiscover to configure the profile automatically.Now we are trying to do the exact same thing with the new company's Exchange server but nothing is working.

When I configured the Outlook client on a laptop that was connected to our visitor's Internet connection (not behind our firewall) , everything worked instantly. My computer at home worked really well too. As soon as a computer is in our internal network, it is unable to connect to the new Exchange server.

All Outbound traffic is allowed in our firewall policy rules and there shouldn't be any problem. I am trying to troubleshoot the issue since everything seems to be working fine on the remote Exchange server and the TMG Forefront 2010 seems to be the obvious issue.

I'd really appreciate if someone could guide me in the troubleshooting of this issue.

Here is some additional information :

  • Outlook clients 2007, 2010, 2013 are in our internal networks.
  • I have tried the connection on every client outside our network and they all work perfectly
  • We used to have an internal Exchange server, however we switch to Office 365 a good while ago and all email server access rules in the TMG have been deleted since. There are no traces of this server in our Active directory or DNS either
  • The connection to the new Exchange server works if the client computer is connected through VPN to the new office before the autodiscover setup is configured.
  • The profile created through VPN cannot load if the VPN connection is on full-time.
  • The new Exchange server is running Exchange 2010

Thank you,


share|improve this question
Use the logging section in TMG to look at the requests from a client machine to the Exchange server - is anything being denied? – Chris McKeown Mar 26 '13 at 12:54
To add to what @CMcKeown said, Logs and Reports -> Edit Query -> [Action] [Not equal] [Connection Status] -> Start Query should grab all traffic passing through the TMG. Should be able to to tweak the settings from there to grab all the traffic you are interested in. – jmreicha Mar 26 '13 at 14:58

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