How to “bounce” or proxy XMPP accounts

I think I'm looking for an XMPP bouncer. But XMPP federation is a confusing thing for someone who's never dug into it before, so I'm having trouble evaluating solutions or even searching for the right things. I know that I don't need a full standalone XMPP server, at least not in the traditional sense of wanting to self-host my chat.

I want to have an always-on service that:

• Connects to my Gmail chat account (as a client) as well as my other XMPP accounts and collects messages sent to these accounts while I'm offline
• Can forward these messages to me (i.e. via email), ideally according to rules I define
• Ideally lets me point my XMPP client directly to the service and sends me messages I missed while offline when I connect (like IRC bouncers do)
• Ideally keeps chat logs in some portable format

Am I looking for an XMPP bouncer? Or is there some other way I could go about achieving these goals through the the XMPP protocol? I think what I'm looking for is more of an XMPP client than an XMPP server—does that even make sense?

Is it even possible to have a service that acts as an intermediary proxy between me and an existing XMPP server, but passes chats and rosters through transparently without looking funny on either end? I'm thinking it would look roughly like this:


Me <----> My service <----> My identity on Google chat <-----> My Google contacts


I've done quite a bit of searching and have come up with very little.

• Spectrum looks like the most promising one. However, I confess that their documentation confuses me a little and I don't exactly know how I would go about configuring it to meet my criteria.
• xmppbnc, which is named right but isn't very active. According to a Redditor, they couldn't get it to connect to a multi-user chat.
• znc-xmpp, an XMPP plugin for ZNC. Zero documentation and no activity means I have no idea if or how this plugin would work.
• Smuxi, which as far as I understand it, only works with the Smuxi client. I want this to take connections from any XMPP client.