[Dovecot] IMAP-proxy or not with sogo webmail and dovecot backend

[Ed W]

On 13/02/2012 19:43, Jan-Frode Myklebust wrote:
> On Mon, Feb 13, 2012 at 11:08:48AM -0800, Mark Moseley wrote:
>> Out of curiosity, are you running dovecot locally on those webmail
>> servers as well, or is it talking to remote dovecot servers?
> The webmail servers are talking with dovecot director servers which in
> turn are talking with the backend dovecot servers. Each service running
> on different servers.
>
> 	Webmail-servers ->  director-servers ->  backend-servers
>

I think the original question was still sensible.  In your case it seems 
like the ping times are identical between:
     webmail -> imap-proxy
     webmail -> imap server

I think your results show that a proxy has little (or negative) benefit 
in this situation, but it seems feasible that a proxy could eliminate 
several RTT trips in the event that the proxy is "closer" than the imap 
server?  This might happen if say the imap server is in a different 
datacenter (webmail on an office server machine?)

I'm also pleased to see that there is little negative cost in using a 
proxy... I recently added imap-proxy to our webmail setup because I 
wanted to log "last login + logout" times.  I haven't quite figured out 
how to best log "logout time" (Timo, any chance of a post logout script? 
Or perhaps it's possible with the current login scripting?).  However, 
using imap-proxy has the benefit of "clustering" logins a little and 
this makes log files a little easier to understand in the face of users 
with desktop mail clients plus webmail users.  Possibly this idea useful 
to someone else...

Thanks for measuring this!

Ed W