[Dovecot] transparent proxy

[Mark E. Mallett]

I'm excited to see that dovecot 1.0-test series supports
transparent proxy, but that excitement is muted by:

 - the recommendation to avoid 1.0 at present;
 - the requirement to use SQL authentication.

I guess I could ignore the first, but the second is sticky.  How
hard would it be to hack a different sort of proxy server cue
into the authentication?  Perhaps one of:

If authenticating via passwd, use a gid as an index into a server
table (or perhaps have the group name be a server name),

If passwd authentication fails, try a starting the proxy to
a specific other server and see if one can log in there.

Or something else..  I dunno, I'm just looking not to install a
SQL server just for this.

mm