Defer email via LMTP when there is 'no space left on device' instead of rejecting it

[Andrzej A. Filip]

On 08/10/2014 12:31 AM, Timo Sirainen wrote:
> On 10 Aug 2014, at 01:19, Timo Sirainen <tss at iki.fi> wrote:
> 
>>> I'd really like to hear Timo's view on having lmtp do a (configurable)
>>> DEFER when the disk is full which is, most likely, a "temporary" error.
>>
>> My opinion: It shouldn't be configurable - it should always cause temporary error. The only thing I'm slightly worried about is if write failures because of "user's filesystem quota full" will always return EDQUOT error for write() instead of ENOSPC, but I suppose they will in any modern OS. And it would require changing MAIL_ERROR_NOSPACE definition a bit inside Dovecot, but that's less of an issue.
> 
> And a bit more generic statement about anything related to errors in Dovecot:
> 
> Problems that admins can solve are temporary errors for users and the'll need an error logged. Problems that are caused by users themselves (like over quota) are usually not temporary errors and they shouldn't have errors logged (since admin can't usually do anything about them anyway).

Do you plan to support MTA queries about mailbox status (overquota,no
space left on device)?  It would allow MTA to deploy its own policies
before sending "RCPT TO:" reply. "Socket map" protocol may be handy.