[exim] control flow in ACLs

Hi,

I suspect I am missing the obvious here and am fairly certain that I am
suffering from wood for trees syndrome, so apologies in advance for
sounding like an idiot.

I have a whole load of ACLs that work fine for HELO tests, sender
verification etc etc:

        deny    message         = Restricted characters in address
                domains         = +all_domains
                local_parts     = ^[.] : ^.*[@%!/|]
                log_message     = "Restricted characters in address"

        deny    message         = Rejected, $sender_host_address listed
in $dnslist_domain\n$dnslist_text
                dnslists        = zen.dnsbl.domain.masked
                log_message     = Found in $dnslist_domain
($dnslist_value) SPAMHAUS-DENY

        require verify          = sender
                log_message     = "Unable to verify sender:
$sender_address"

What I want to do is, if the incoming email matches any of our white
lists to be able to selectively bypass selected ACL statements. So for
example if I know that mail is coming in from friendly.host.com (as it
is whitelisted) - which I can match, log and set an acl variable on:

    warn         senders        = +whitelisted_senders
            log_message     = "whitelisted sender"
            set acl_m_whitesender = true

This is straight forward enough.

The bit that has me scratching my head (well banging against a desk
today), is combining the newly set acl variable with an if condition in
an ACL statement later on in order to give control flow.

So for example:

            deny    message         = Rejected, $sender_host_address
listed in $dnslist_domain\n$dnslist_text
                condition        = ${if !eq
{acl_m_whitesender}{true}}
            dnslists        = zen.dnsbl.domain.masked
                log_message     = Found in $dnslist_domain
($dnslist_value) SPAMHAUS-DENY

I know I am probably missing the obvious - but it has been a long day!

Many thanks

Paul