Changing the name of a compressed file

[Peter West]

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

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 235 bytes
Desc: Message signed with OpenPGP
URL: <http://dovecot.org/pipermail/dovecot/attachments/20170610/465cd5ec/attachment.sig>