On Nov 6, 2008, at 8:28 PM, Giorgenes Gelatti wrote:

I failed in finding the answer in the wiki so i'm asking it here.

In average, how much the dovecot's indexes increase the usage of
storage, compared to a standard maildir mailbox?

Maybe 10-20%.

I believe it would be a function of the number of messages instead
of the message's size. Is there a known aproximated function for that?

dovecot.index.cache file takes the most space. It contains cached data
that client has wanted before, such as some specific headers. So it's
a function of number of messages, what clients are used and how large
the cached headers are.