Question: outlook.pst has reached maximum size 2007?
Answer: In Outlook 2003 and Outlook 2007, the maximum recommended size of a Unicode pst-file and ost-file has been limited to 20GB. In Outlook 2010, 2013 and 2016, this recommended limit has been set to 50GB. You can increase (but also decrease) this limit via the Registry or via Group Policies.