I had a crazy issue in outlook last month with exchange 2013 and outlook 2013. Sometimes the public folder disappeared in the left pane. So there was only left the mailbox hierarchy. The only way to fix this was to create a new outlook profile. Then all things were fine for some hours. Then the problem occurred again.

I called microsoft support and they did not know a solution.

Finally, after some weeks of investigation, I found out that the reason for the problem was a wrong configured DHCP-Server.

The clients are getting the dns settings from dhcp. The primary dns server was the domain controller. The seconday dns server was our dns server from out internet provider. This second dns server was the problem. I removed it and all things were fine.

I think that the primary dns server was not responding for some reason. Then the client was using the secondary dns server. Since this was the internet provider dns server it did not know anything about our exchange server. So it could not resolve „exchange.company.local“. And the public folders disappeared. Strange, the mailbox was working without problems.

I think microsoft has changed the behavior of outlook 2013. If the public folder are not available outlook does not try to reconnect them anymore. So I had to recreate the profile everytime.

My conclusion to this is: Only use dns servers within you domain. My approach to use the provider dns server as a secondary service was the problem. Unfortunately, this setting was great in the past: If the server was down the people could surf in the internet anyway. Now this is not possible anymore.