On 28 Jun 2016, at 16:07, Luca Lesinigo <luca@lm-net.it> wrote:

We are preparing an IMAP proxy based on dovecot-2.2.22, basic proxy functionality is already working and I’m trying to understand if having the FTS service configured on the dovecot *proxy* would be of any use.

I do suspect it would be useless, I guess dovecot in imap proxy mode just forwards any command to the backend and does not bother to do anything about it, but I’m failing to find a definitive answer in the documentation. If I am guessing correctly, an fts service would only be useful if configured and working on the actual backend.

Can anyone clarify my doubts?

If you want to use doveadm fts optimize/rescan commands via doveadm proxy, you need to load fts plugin on the proxy to get the commands. But otherwise there's no reason for it.