[Dovecot] Maildirsize file isn't updated after doing POP

[Nitass Sutaveephamochanon]

Hello,

I have a problem about updating Maildirsize file. It seems that the 
Maildirsize file is not updated after user does POP mail from his maildir. I 
do not want to use any quota limitation in Dovecot. I only want Dovevot to 
update the Maildirsize file after user retrieves his mail. The Maildirsize 
file is created by Postfix. Would it be possible to do like this? How can I 
configure it? Could you please advice me?

The Dovecot version is 1.0.7.

Thank you very much,
Nitass