Thanks for your answer, i mentioned that it worked with sawin32 so there is no problem, but with cygwin and perl with cpan updating to the latest release is possible that is why i preferred it.
And as far as i understand the principle of the solution cygwin should also work.
After a reboot domino and/or the agent did not find spamassassin while it was in the path, when i copied it to c:\windows\system32 folder it worked.
Keep up the good work and have a nice day.