Changing the name of a compressed file

[Peter West]

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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