Suggested feature and contribution

Egoitz Aurrekoetxea egoitz at
Fri Jul 19 03:47:54 EDT 2019

Thanks a lot Bron!

Yeah I saw your commit in 2015… I think the idea is fine but perhaps an alert should be better for that instead of a restriction…. Normally people is not going to do this kind of silly things… And when done is normally a mua driven crazy (we know everyone which mua I’m talking about :p )….

I’ll tell about this fix to a customer of us who removed tons of folder… weren’t at saremail_restore (our deleted items recover system) and I started taking a look at what was going and arrived to this lines of mboxlist.c (I think it was..)…


Egoitz Aurrekoetxea
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egoitz at <mailto:undefined> <>
Antes de imprimir este correo electrónico piense si es necesario hacerlo.

> El 19 jul 2019, a las 2:13, Bron Gondwana <brong at> escribió:
> On Fri, Jul 19, 2019, at 10:09, Bron Gondwana wrote:
>> On Thu, Jul 18, 2019, at 19:09, Egoitz Aurrekoetxea wrote:
>>> Good morning,
>>> When using delete_delayed if someone removes a big folder (that one with more than 20 subfolders anywhere below it) in mboxlist_delayed_deletemailbox() only last 20 are preserved. We think it could be a good idea to preserve all and to have a parameter for configuring it. The reason for that, is that we use delete_delayed for storing the removed content remotely with the customer hired retention period in slow disk space. Perhaps could be a good idea something like : 
>>> In mboxlist_delayed_deletemailbox() : 
>>> If (!preserve_delete_delayed_folders_always)
>>> {
>>>     /* keep the last 19, so the new one is the 20th */
>>>     for (i = 0; i < (int)existing.count - 19; i++) {
>>>         const char *subname = strarray_nth(&existing, i);
>>>         syslog(LOG_NOTICE, "too many subfolders for %s, deleting %s (%d / %d)",
>>>                newname, subname, i+1, (int)existing.count);
>>>         r = mboxlist_deletemailbox(subname, 1, userid, auth_state, NULL, 0, 1, 1,
>>>                                    keep_intermediaries);
>>>         if (r) goto done;
>>>     }
>>> }
>> Hmm.... yeah, OK.  This is actually buggy in that case!  The intended behaviour was to avoid a Denial of Service attack where you would create and delete the same mailbox name millions of times - however, the whole concept is bogus because there's nothing stopping somebody creating and deleting folder000001 through folderFFFFFF and creating the same attack.
>> I suggest that we just remove this whole silly check entirely, and if we want a similar level of attack protection we do something smarter like a quota for total folders+deleted folders that haven't been cleaned up yet - set it high enough that anybody hitting that is clearly doing something wrong, and require the administrator semi-manually clean up the deleted folders in order to re-allow folder creation.
>> Cheers,
>> Bron.
> I've pushed commits to master and 3.0 to remove this check.
> --
>   Bron Gondwana, CEO, Fastmail Pty Ltd
>   brong at <mailto:brong at>
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