[Exim] Beginners help

I am trying to get Exim 4 configured and connected to MySQL. I am
running this on RH9. As far as I know I have given grant permissions to
exim in MySQL so at least it should be able to read the database...
permissions wise.

I am using this command in the router section of the configure...

user = {lookup mysql {SELECT username FROM mail WHERE domain =
'${quote_mysql:$domain}' AND username = '${quote_mysql:$local_part}'
}{$value}fail}


In the log I get the following....

Failed to expand user string " {lookup mysql {SELECT username FROM mail
WHERE domain = '${quote_mysql:$domain}' AND username =
'${quote_mysql:$local_part}' }{$value}fail}" for the domain_aliases
router: "lookup" failed and "fail" requested.


I have a table set up in mysql called 'mail' etc. with a filed called
'username' and 'domain'...

The thing is I don't really understand how to setup a user account with
exim.... how should I do this?

I would also like to have a web front end to this for admin. What's the
best tool for this? Any recommendations?

Thanks in advance.
Ronan.