Flag \NonExistent (and tombstones)

Hello everyone,

I have noticed, that "lm" (in cyradm) lists mailboxes that have been 
deleted months ago, and flags them with \NonExistent.

After some googling I found that there is something callen "tombstone" 
and gets removed after some time. I found in syslog that "tombstones" 
indeed exist and get cleaned after some time, but this happens only for 
"subfolders", not deleted user's INBOX.

Are "tombstones" and \NonExistent the same thing?
What is their use? Why does cyrus leave such traces of deleted stuff?
How do I get rid of them ?

I use:
delete_mode: immediate
expunge_mode: semidelayed

recently I upgraded from 3.2.x to 3.6.x (debian 10 -> 11), and those 
\nonexistent mailboxexs were deleted before the upgrade. It was just 
when I ran reconstruct and was checking if everything is OK when I 
noticed their (non)existence.

-- 
best regards
         Vladislav Kurz

------------------------------------------
Cyrus: Info
Permalink: https://cyrus.topicbox.com/groups/info/T6de1a094c5ccedb3-Mfc127975cea5e6a180153135
Delivery options: https://cyrus.topicbox.com/groups/info/subscription