[Dovecot] Run script before delivery

Hi

Is it possible to run one script before the "real" delivery of a message (with lda, or before the execution of the sieve scripts) but after the creation of necessary folders (Dovecot automatically creates the folders for virtual users)? I want to to this to manually create a fixed empty sieve script in each user home folder, so in the global sieve script include that personal script, because if personal script doesn't exists, global script is not executed, or am I wrong?

Thanks in advance.