[Dovecot] mdbox expunge purge question

[Daniel Luttermann]

Hi,

I'm testing Dovecot 2.0rc2 with mdbox mail format and I'm not sure
what this exactly means:

http://wiki2.dovecot.org/MailboxFormat/dbox

Quote from wiki page:

=====
Expunging a message only decreases the message's refcount. The space
is later freed in "purge" step. This may be done automatically within
the session or later in a nightly cronjob when there's less disk I/O.
=====

So this means that even if a user deletes a mail the space gets only
freed if I run "doveadm purge" manually or an user requests this over
his mail client?

When the expunge plugin is used the deleted mails are stored in a
special mailbox in the users mailbox so it's needed to use the expire
plugin too if this should be done automatically?

Is it recommend to run "doveadm purge" periodically if mdbox is used?

Btw: when I try to run

doveadm -Dv expunge -u testuser at dlutt.de mailbox Trash savedbefore 30d

for example I get such an error:

doveadm(root): Debug: Loading modules from directory: /usr/lib/dovecot/modules
doveadm(root): Debug: Module loaded: /usr/lib/dovecot/modules/lib01_acl_plugin.so
doveadm(root): Debug: Loading modules from directory: /usr/lib/dovecot/modules/doveadm
doveadm(root): Error: dlopen(/usr/lib/dovecot/modules/doveadm/lib10_doveadm_expire_plugin.so) failed: /usr/lib/dovecot/modules/doveadm/lib10_doveadm_expire_plugin.so: undefined symbol: expire_set_lookup
doveadm(root): Error: dlopen(/usr/lib/dovecot/modules/doveadm/lib10_doveadm_quota_plugin.so) failed: /usr/lib/dovecot/modules/doveadm/lib10_doveadm_quota_plugin.so: undefined symbol: quota_user_module

Plugin expire or expunge is not currently enabled in Dovecot's config.

Thanks for any hints.

Daniel