Outlook Clients for Exchange 2013 Prompt for Password

I have a co-existence of versions 2007 and Exchange Server 2013 CU2 and currently have the following problem: 

- Customers now where I performed the migration to the 2013 version, when starting Outlook is always asking for password. The settings for Outlook Anywhere are as follows: 

RunspaceId                         : b43cd829-a81f-4b00-bb4d-73389c9df50d
ServerName                         : EXCH-HTCA13
SSLOffloading                      : False
ExternalHostname                   : webmail.first.pt
InternalHostname                   : exch-htca13.first.pt
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}
XropUrl                            :
ExternalClientsRequireSsl          : True
InternalClientsRequireSsl          : True

Can anyone help me identify the problem?