[Dovecot] vacation messages (dovecot lda cmusieve)

Hi,

I am experiencing some problems with vacation messages feature. Using dovecot from alpha4 to 1.0.rc6 with lda from cvs, when setting up a vacation message, there is a parameter ":days" which specifies the interval between auto-reply messages. After the first reply, should wait that amount of days before sending a new reply to the same sender. The list of sender addresses is to be kept in $maildir/.dovecot.lda-dupes

Now, what happens is that at random intervals, auto-replies are sent. It happens with any account, from thirty minutes to one hour maybe.

How is it possible ? How to fix it ?