If you are using an old version of powermta,possibly version 3+,then you might easily upgrade to the latest version.
Just download the latest file to your server and install it.
Start your pmta in debug mode : pmtad –debug and see if it is running properly.
You might have several or more outdated directives in config file.Search them in the userguide and replace with the currently used directives.
That is all!