Conditional unixhierarchysep ?

[Jason Fesler]

Is it possible to, for some clients, have unixhierarchysep be enabled, but
not touch other clients?  I only have one single machine for testing, and
I'm loathe to change things on everyone without testing things out myself
(specifically, the user pain of migration).

Alternately, can this be done on a per instance of imapd basis, ie on a
different port number?

Kind of ditto for altnamespace ..  :-)