dovecot - Feb 2019 - expunge not removing attachments?

I have a large mail backup folder backup at backup.invalid; I'm cleaning
up daily like this:

infimum=`date -d "-4 day" +"%Y-%m-%d"`
doveadm expunge -u backup at backup.invalid mailbox INBOX SAVEDBEFORE $infimum 
doveadm purge   -u backup at backup.invalid

yet I see this:

# find attachments/ -type f -ctime +5 | wc -l
7522
# find attachments/ -type f | wc -l
127579

# find attachments/ -type f -mtime +5 | wc -l
14361
# find attachments/ -type f | wc -l
127793

About 5.9% of the files in attachments and below are older than 5 days.
Why? Is that normal?

using dovecot 2:2.3.1-1 from the official repos.
-- 
Ralf Hildebrandt
  Gesch?ftsbereich IT | Abteilung Netzwerk
  Charit? - Universit?tsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de

* Ralf Hildebrandt <Ralf.Hildebrandt at
charite.de>:
> I have a large mail backup folder backup at backup.invalid; I'm
cleaning
> up daily like this:
> 
> infimum=`date -d "-4 day" +"%Y-%m-%d"`
> doveadm expunge -u backup at backup.invalid mailbox INBOX SAVEDBEFORE
$infimum
> doveadm purge   -u backup at backup.invalid
> 
> yet I see this:
> 
> # find attachments/ -type f -ctime +5 | wc -l
> 7522
> # find attachments/ -type f | wc -l
> 127579
> 
> # find attachments/ -type f -mtime +5 | wc -l
> 14361
> # find attachments/ -type f | wc -l
> 127793
> 
> About 5.9% of the files in attachments and below are older than 5 days.
> Why? Is that normal?
> 
> using dovecot 2:2.3.1-1 from the official repos.
I retried this today (2:2.3.4.1-1~bionic):

# find attachments/ -type f -ctime +5 | wc -l
193121
# find attachments/ -type f | wc -l
301885

193121 of 301885 (64%) are older (ctime) than 5 days, although I just purged
everything older than 4 days?


# /home/copymail# find attachments/ -type f -mtime +5 | wc -l
201629
# /home/copymail# find attachments/ -type f | wc -l
301900

201629 of 301900 (66.7%) files are modified (mtime) more than 5 days ago,
although I just purged everything older than 4 days?

-- 
Ralf Hildebrandt
  Gesch?ftsbereich IT | Abteilung Netzwerk
  Charit? - Universit?tsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de

On 12 Feb 2019, at 03:45, Ralf Hildebrandt via dovecot <dovecot at
dovecot.org> wrote:
> 201629 of 301900 (66.7%) files are modified (mtime) more than 5 days ago,
although I just purged everything older than 4 days?
I had problems with this a few years ago, and resorted to simply using find to
remove the files from the file system

/usr/bin/find /usr/local/virtual/*/.Junk*/{cur,new} -type f -mtime +7 -name
?*=*" -delete 2> /dev/null
/usr/bin/find /usr/local/virtual/*/.Trash/{cur,new} -type f -mtime +7 -name
?*=*" -delete 2> /dev/null