[Exim] RBL settings via MySQL

I'm researching an idea to allow virtual domains to have different
settings for rbls by storing the settings in mysql. There are two
important considerations.

1. Can the rbl list be obtained from mysql in the acl.
2. Will be performance be good enough to make is usable.

I'm thinking the setting would be something like this:

RBL_LIST = SELECT rbl_list FROM domains WHERE domain = '${domain}';
deny message = Sender has been blacklisted
dnslists = ${lookup mysql{RBL_LIST}}

But I'd really like to obtain the deny message from the database as
well so that each blacklist can have it's own message, except I don't
see how that could be possible.

Assuming this can be done, the next step would be to add an RBL GUI
for easy configuration (possibly in Vexim).

Comments and suggests would be most welcome.

Rossz