[otrs] how to reduce Postmaster default poll interval

Hi, I am using otrs 2.4.7 on windows OS and i am using postmaster mail account to generate tickets but it is taking 10 min to generate tickets for received mails i have tried changing time interval to 1 min by making changes in OTRS\var\cron\postmaster_mailbox.dist file but no luck can any one guide me step by step...where to make the changes to poll postmaster mail in every one min interval. Regards, -- G.Siva Krishna