[Dovecot] zlib config questions

Sven Hartge sven at svenhartge.de
Fri Dec 6 21:28:50 EET 2013

Terry Barnum <terry at dop.com> wrote:

> I'm curious how many people here use the zlib plugin. Is it common or
> is drive space cheap enough that it's not worth it to run the risk of
> potential problems?

HDD space may be cheap, but is also slow, therefor IOPS are very

I compress the mail using zlib, because even a very slight compression
rate as 3 reduces the IOPS by more than 50% in my measurements and in my
environment. As long as you don't plan to use a Raspberry Pi as your
Dovecot server, todays CPUs are easily able to cope.

And, please anybody correct me if I am wrong, if you use imap_zlib then
the IMAP connection is compressed as well which may allow Dovecot to
skip the decompressing state completely and just deliver the compressed
stream directly. (Althought I don't know anymore where I read this and
may be totally wrong and bogus. Please confirm with anyone knowing the
code. Thanks.)

Also reducing the needed space is a welcome bonus for me. 


Sigmentation fault. Core dumped.

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