Outlok 2007 with latest hotfixes
Freshly migrated mailboxes
Gives the error 

Can't open outlook-The set of folders cannot be opened

Cert has internal FQDN name. Encryption is disabled

Any pointers?

Hi,

See a correct support matrix for Exchange 2013 to understand the patch level required for Outlook 2007 to connect with Exchange 2013 here: http://technet.microsoft.com/en-us/library/aa996719(v=exchg.150).aspx

Hi Tijl,

Outlook 2007 are known for it's limited support from Exchange 2013. The best option here is to go for updating to Outlook 2010 at least.

Hi Tijl,

Outlook 2007 are known for it's limited support from Exchange 2013. The best option here is to go for updating to Outlook 2010 at least.

Does the certificate have the server name?

That was apparently the solution here:

http://social.technet.microsoft.com/Forums/exchange/en-US/1ae67f48-d1ba-44b5-a3c7-4e9a5e955f3e/outlook-2007-cannot-connect-to-exchange-2013?forum=exchangesvrclients

Hi,

To narrow down the cause, Id like to recommend the following troubleshooting:

1. Try to recreate your profile and have a test.
2. Check if the problematic Outlook 2007 cannot work for multiple users.
3. Check the connection status when the error appears.

Thanks,