On 12.4.2010, at 20.29, Mike Abbott wrote: >> except if auth { mechanisms } doesn't have PLAIN > > Precisely. Hence, X-PLAIN-SUBMIT.
So you're thinking of an installation that is for example Kerberos-only and only wants to advertise GSSAPI to clients, but still supporting PLAIN to submit server? Maybe the solution then in v2.0 is: auth_mechanisms = gssapi remote submit.server.org { auth_mechanisms = gssapi plain } (although ip-specific settings don't currently work for auth settings, but that's a solvable problem.)