Re: MX preference

[mea@nic.funet.fi]

> 	Hi!
> 
>	How I can setup zmailer for using MX before local routes-table?
> 
> 	For example, when my relay server gets mail for our client who has
>     SMTP routes preferable and UUCP routes as backup zmailer must do MX
>     lookup and if and only if SMTP-server does not respond send this mail
>     at UUCP.

  Can't support that.  The problem being the phase, where the transport-
specification file is generated, which is then used to specify what the
scheduler will do -- i.e. run smtp transport agent which does MX lookup
plus connection attempt.


  Well, in THEORY we could support it, but the XOR-hooks in system have
not been completed.   Their theory is roughly as follows:

	- encode a set of XOR recipients into TA-spec file
	  (assume two XOR sets, id's 12 and 34)
		X     12 smtp host user priv
		X     12 uucp host user priv
		X     34 smtp host user priv
		X     34 smtp host user priv
		X     34 uucp host user priv
	- run only one of those recipients per XOR-set at a time.
	  When any of them succeeds, rest MUST be ignored.

Mechanisms exist within the router (mostly, anyway), but the scheduler
does need new algorithms to handle this type of threads.

Also the interlock issues are not quite trivial in this case :-/
(Perhaps fcntl regional locks within a file could help ?  Hmm..)

Anyway, implementing that is not of any priority to me. (yet)

> 	Thanks.
> -- 
> 	CU, Victor Gamov

/Matti Aarnio <mea@nic.funet.fi>