[Dovecot] Proxying Performance vs imapproxy

[Ed W]

You didn't get much answer to this - I'm probably not the best person to 
answer, but

> Are there any performance benefits to using a proxying server, or is it just
> for splitting mailstores?
>   

I think this is the main reason for the proxying option.  It would 
appear that others have measured the performance load of the proxy task 
and found it near negligible?  Hence it seems possible to use a bunch of 
backend servers and a few frontend servers to forward the user to the 
correct backend server.  I believe each connection needs to be setup 
each time though, so for sure some more advanced proxies with persistent 
caching of connections may offer a performance improvement if your 
servers are loaded due to the login part (but I guess measure this first 
before assuming it's so?)

Some have even used the backend servers as the frontend proxy servers, 
ie if you only have a small number of servers then make them all 
frontend and backend servers, eg with three servers you have a 1 in 3 
chance of getting straight onto the correct server, otherwise proxy over 
to the correct server...

Good luck

Ed W