10G mails use 90G on disk

[Aki Tuomi]

> On 29/01/2021 12:41 Markus Schönhaber <dovecot at list-post.mks-mail.de> wrote:
> 
>  
> Hello,
> 
> on a system I administer the disk where Dovecot's mailstore (mdbox)
> resides got filled up to the brim although the combined quotas for the
> users are much smaller than the disk's capacity.
> 
> For one user I see the following:
> 
> doveadm quota get -u <USER>@<DOMAIN>
> Username         Quota name Type       Value    Limit
>                           %
> <USER>@<DOMAIN>  User quota STORAGE 10231248 20971520
>                          48
> <USER>@<DOMAIN>  User quota MESSAGE    11176        -
>                           0
> 
> So this user has used ~10G of his 20G quota. But looking at the space
> used on disk:
> 
> # du -hs /var/spool/vmail/mail/<DOMAIN>/<USER>/storage/
> 90G     /var/spool/vmail/mail/<DOMAIN>/<USER>/storage/
> 
> What might be the reason that mail size and disk space used differ so much?
> And most of all: how can I prevent that from happening?
> 
> Regards
>   mks
> 
> 
> # doveconf -n
> # 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf
> # Pigeonhole version 0.5.13 (cdd19fe3)
> # OS: Linux 4.19.0-13-amd64 x86_64 Debian 10.7 ext4
> # Hostname: …
> auth_mechanisms = plain login
> dict {
>   quota = pgsql:/etc/dovecot/dovecot-dict-sql.conf.ext
> }
> imap_id_log = *
> login_log_format_elements = user=<%u> method=%m rip=%r lip=%l lport=%a
> mpid=%e %c
> mail_home = /var/spool/vmail/home/%d/%n
> mail_location = mdbox:/var/spool/vmail/mail/%d/%n
> mail_plugins = " quota acl"
> managesieve_notify_capability = mailto
> managesieve_sieve_capability = fileinto reject envelope
> encoded-character vacation subaddress comparator-i;ascii-numeric
> relational regex imap4flags copy include variables body enotify
> environment mailbox date index ihave duplicate mime foreverypart extracttext
> namespace inbox {
>   inbox = yes
>   location =
>   mailbox Drafts {
>     special_use = \Drafts
>   }
>   mailbox Entwürfe {
>     special_use = \Drafts
>   }
>   mailbox Entw&APw-rfe {
>     special_use = \Drafts
>   }
>   mailbox "Gelöschte Objekte" {
>     special_use = \Trash
>   }
>   mailbox "Gel&APY-schte Objekte" {
>     special_use = \Trash
>   }
>   mailbox "Gesendete Objekte" {
>     special_use = \Sent
>   }
>   mailbox Junk {
>     special_use = \Junk
>   }
>   mailbox Sent {
>     special_use = \Sent
>   }
>   mailbox "Sent Messages" {
>     special_use = \Sent
>   }
>   mailbox Trash {
>     special_use = \Trash
>   }
>   prefix =
>   separator = /
> }
> passdb {
>   args = /etc/dovecot/dovecot-sql.conf.ext
>   driver = sql
> }
> plugin {
>   acl = vfile
>   mail_log_events = delete undelete expunge copy mailbox_delete
> mailbox_rename
>   mail_log_fields = uid box msgid size
>   quota = dict:User quota::proxy::quota
>   recipient_delimiter = +
>   sieve = file:~/sieve;active=~/.dovecot.sieve
>   sieve_redirect_envelope_from = orig_recipient
> }
> protocols = " imap lmtp sieve"
> service auth-worker {
>   user = $default_internal_user
> }
> service auth {
>   inet_listener {
>     port = 12345
>   }
>   unix_listener /var/spool/postfix/private/auth {
>     group = postfix
>     mode = 0666
>     user = postfix
>   }
> }
> service dict {
>   unix_listener dict {
>     group = vmail
>     mode = 0600
>     user = vmail
>   }
> }
> service lmtp {
>   unix_listener /var/spool/postfix/private/dovecot-lmtp {
>     group = postfix
>     mode = 0600
>     user = postfix
>   }
> }
> service stats {
>   client_limit = 10000
>   unix_listener stats-writer {
>     group = vmail
>     user = vmail
>   }
> }
> ssl_cert = </etc/letsencrypt/live/<DOMAIN>/fullchain.pem
> ssl_dh = # hidden, use -P to show it
> ssl_key = # hidden, use -P to show it
> userdb {
>   args = /etc/dovecot/dovecot-sql.conf.ext
>   driver = sql
> }
> verbose_proctitle = yes
> protocol lmtp {
>   mail_plugins = " quota acl quota sieve"
> }
> protocol lda {
>   mail_plugins = " quota acl sieve"
> }
> protocol imap {
>   mail_plugins = " quota acl imap_quota acl"
> }
> remote 192.168.1.0/24 {
>   protocol imap {
>     disable_plaintext_auth = no
>   }
> }

mdbox format requires you to periodically run

doveadm purge -u user

to cleanup deleted mails from the mdbox storage. mdbox has feature that you can use mail_location mdbox_deleted to access any deleted emails if you need to recover them, but it also requires you to purge the storage now and then.

Aki