Hi Subburaj,
When you try to publish a custom Outlook form, this is a good document for you:
How to determine where to publish a custom Outlook form
http://support.microsoft.com/kb/290802
If you want to know the permission for user who use Organizational Forms Library to publish the Outlook forms, here is related documents for you:
How to Create an Organizational Forms Library in Exchange 2007
http://technet.microsoft.com/en-us/library/cc540468(EXCHG.80).aspx
Create an Organizational Forms Library
http://technet.microsoft.com/en-us/library/gg236889.aspx
Thanks,
Evan