Compress by zlib only selected Maildir folders

[David Pottage]

On 2020-05-12 10:35, filbar at centrum.cz wrote:
> Hello,
> is it possible to compress by zlib only selected folders? My e-mail
> accounts have archive folder and this folder contains old comunications
> with my customers and this I use very rare, so I want to compress them
> by zlib to save space. Is this possible?

Presumably you are the admin for the email server?

If so, you could move your mail store to a btrfs or zfs filesystem with 
compression support. I am not sure about zfs, but I know that with btrfs 
it is possible to set different default compression settings for 
individual files & directories as well as the FS as a whole.

You should ask yourself if it is worth the trouble. Disk space is cheap, 
and emails tend to be reasonably small, so it might be more prudent to 
just buy some larger disks. Also if all the disk space is being used by 
attachments, then you should check if they are compressible, as image 
files or encrypted files are usually not.

I am running a personal mail server using dovecot with the email store 
on a btrfs volume, but I have not enabled compression because I care 
more about speed and reliability. An additional advantage of btrfs is 
that you can use the snapshot feature to make backups more reliable.
-- 

David Pottage