[otrs] some further actions on ticket-creation through incoming mail

Hi, among many other incoming mails, our OTRS receives some special (marked) mails. Now, I want some special data contained in this mail-body to be added to a csv-file. I tend to use PostMaster::PreFilterModule###4-CMD for this purpose. The CMD called is a perl-script which applies regex to find the data an apped it to csv. Is this the right way? Any other/better suggestions? Bye, Alex