Postbox cannot find Profile folder after running "Speedupmymac"

After running the software "Speedupmymac", some customers see the error:  "Profile Missing. Your Postbox profile cannot be loaded. It may be missing or inaccessible."

If this happens, most likely your cache folder has been locked by this program.  

Within ~[your home folder] / Library / Caches / please make sure that the com.postbox-inc.postbox folder has permissions set to "everyone: read only".  You can set these permissions by selecting the com.postbox-inc.postbox folder and then selecting "Get Info" from the File menu.