Question of a procmail newbie

I have a problem:


I recieve e-mails with the body like this:

Category: abc
Subcategory: def
File: ghi


I'd like to put the body of this e-mail to the file:

abc/def/ghi

In this case I should do "mkdir -p abc/def" at first.


How could I write a .procmailrc file for this?

Please, answer me directly to my e-mail, not to mailing list.