You can't. Only the root Contacts Folder in your default PST file can be
your default Contacts Folder.
I assume you didn't really mean OST file. That makes no sense.
--
Russ Valentine
"Paolo" wrote in message
news
Hi,

I would like to set a folder located in a PST file as my primary (and
default) Contact folder.

I defined an e-mail account and, by default, the Contact folder that is
used
when I click on "New Contact" is the Contact folder located in the same
PST
or OST where I have my default Inbox and Outbox. That folder is
undeletable
and is the one used for ActiveSync Contact synchronization with Windows
Mobile.

How can I define another Contact folder as my primary/default (and
possibly
undeletable) Contact folder?

--
Plo