Changing the name of a compressed file
Peter West
lists at pbw.id.au
Sat Jun 10 14:10:42 EEST 2017
Ok, I added zlib to imap protocol.
protocol imap {
…
mail_plugins = $mail_plugins zlib
}
Now both imap and lmtp protocols have zlib plugin enabled, and both send and receive mail is compressed.
Peter
> On 10 Jun 2017, at 6:50 pm, Aki Tuomi <aki.tuomi at dovecot.fi> wrote:
>
> Please check that you are not overwriting mail plugins for lmtp. Or post your doveconf -n.
>
> Aki
>
>> On June 10, 2017 at 11:10 AM Peter West <lists at pbw.id.au> wrote:
>>
>>
>> Not sure what you mean. I’m using lmtp to send messages to Dovecot from Postfix.
>>
>>> On 10 Jun 2017, at 6:08 pm, Aki Tuomi <aki.tuomi at dovecot.fi> wrote:
>>>
>>> What's your LDA?
>>>
>>> Aki
>>>
>>>> On June 10, 2017 at 11:01 AM Peter West <lists at pbw.id.au> wrote:
>>>>
>>>>
>>>> Thanks for that Aki.
>>>>
>>>> Follow-up question. I tried to initiate compression by adding
>>>>
>>>> mail_plugins = $mail_plugins zlib
>>>>
>>>> plugin {
>>>> zlib_save_level = 6
>>>> zlib_save = xz
>>>> }
>>>>
>>>>
>>>> to dovecot.conf. I restarted dovecot and sent one message to the server, and one message from the server. Neither was compressed. I changed the save type to
>>>>
>>>> zlib_save = bz2
>>>>
>>>> and repeated. This time the message received (in /var/vmail/<host>/<username>/cur) was not compressed, but the message in /var/vmail/<host>/<username>/.Sent/cur was bzip2 compressed.
>>>>
>>>> Why is the received mail not being compressed? Is this the point of the discussion about compressing old mails?
>>>>
>>>>
>>>>> On 10 Jun 2017, at 4:43 pm, Aki Tuomi <aki.tuomi at dovecot.fi> wrote:
>>>>>
>>>>>
>>>>>> On June 10, 2017 at 5:58 AM Peter West <lists at pbw.id.au> wrote:
>>>>>>
>>>>>>
>>>>>> Concerning Maildir, the wiki page on compression has this:
>>>>>>
>>>>>> All mails must have ,S=<size> in their filename where <size> contains the original uncompressed mail size, otherwise there will be problems with quota calculation as well as other potential random failures. Note that if the filename doesn’t contain the ,S=<size> before compression, adding it afterwards changes the base filename and thus the message UID. The safest thing to do is simply to not compress such files.
>>>>>>
>>>>>> Further down on the same page is this:
>>>>>>
>>>>>> If the file does exist, rename() (mv) the compressed file over the original file.
>>>>>> • Dovecot can now read the file, but to avoid compressing it again on the next run, you'll probably want to rename it again to include e.g. a "Z" flag in the file name to mark that it was compressed (e.g. 1223212411.M907959P17184.host,S=3271:2,SZ).
>>>>>>
>>>>>> These comments seem to contradict each. Or is there a difference between adding the size specifier to the filename and adding a Z flag to the end of the file name?
>>>>>>
>>>>>> --
>>>>>> Peter West
>>>>>> pbw at pbw.id.au
>>>>>> And the great throng heard him gladly.
>>>>>>
>>>>>
>>>>> Keyword is 'base filename'. From the wiki, "The standard filename definition is: "<base filename>:2,<flags>".". Z is a flag.
>>>>>
>>>>> Aki
>>>>
>>
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