Locks directory change

Hello,

it's the first time for me writing to the list, I'm trying to change the location into which the Dovecot's locks are done reserving a special temporary directory on an other partition, then adding to the dovecont.conf the line:

mail_location = maildir:~/Maildir:VOLATILEDIR=/tmp_lock/%2.256Nu/%u

so that through the VOLATILEDIR directive the locks should be written in this path. We observe though that the locks for many users are still done in the real maildir (NFS mounted filesystem) as if in some situations this instruction is not effective. Anybody knows if are there other things to change or to do or what could be the reason? (for instance to login in a specific way or doing a particular operation).

Regards, Federico