dovecot - May 2020 - Deleting messages from filesystem with sdbox mail format

Dear list,
I recently had to delete some messages from an sdbox mailbox, for which 
I used the canonical "doveadm expunge" command without issues.

However I got curious and, on a test mailbox, I deleted an unimportant 
message directly from the filesystem (rm u.650). After removing the 
file, the webmail continued to show it in the mail list - but no text 
was retrieved when I selected it. I supposed this was due to 
dovecot.index.cache and, indeed, deleting the cache got rid of the 
message in the webmail list.

While I understand that it is not recommended (deleting and regenerating 
the index cache is an expensive operation), I wonder if removing a file 
from the filesystem, and regenerating the index cache file, is a safe 
operation when using an sdbox mailstore. Specifically, I would like to 
know if, after a manual filesystem deletion, the main index file 
(dovecot.index) is automatically updated by dovecot (reflecting the 
deletion) or if lingering references are kept in it.

Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it [1]
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8

> On 11/05/2020 16:45 Gionatan Danti <g.danti at assyoma.it> wrote:
> 
>  
> Dear list,
> I recently had to delete some messages from an sdbox mailbox, for which 
> I used the canonical "doveadm expunge" command without issues.
> 
> However I got curious and, on a test mailbox, I deleted an unimportant 
> message directly from the filesystem (rm u.650). After removing the 
> file, the webmail continued to show it in the mail list - but no text 
> was retrieved when I selected it. I supposed this was due to 
> dovecot.index.cache and, indeed, deleting the cache got rid of the 
> message in the webmail list.
> 
> While I understand that it is not recommended (deleting and regenerating 
> the index cache is an expensive operation), I wonder if removing a file 
> from the filesystem, and regenerating the index cache file, is a safe 
> operation when using an sdbox mailstore. Specifically, I would like to 
> know if, after a manual filesystem deletion, the main index file 
> (dovecot.index) is automatically updated by dovecot (reflecting the 
> deletion) or if lingering references are kept in it.
> 
> Thanks.
> 
> -- 
> Danti Gionatan
If you manually change the mailbox contents like that, you need to run doveadm
force-resync to fix the situation.

Aki

Il 2020-05-11 15:54 Aki Tuomi ha scritto:
> If you manually change the mailbox contents like that, you need to run
> doveadm force-resync to fix the situation.
> 
> Aki
Ok, so it means that dovecot will *not* automatically fix the index file 
and I need to reconstruct the index file, right?

Just for completeness: will not fixing the index file (after a manual 
deletion) cause unexpected issues, or "only" lingering reference to a 
delete email?

Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it [1]
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8