Trouble with ACL and Postgre/local_part domain

Hi,
can I use Postgre Lookups in ACL conditions? I can't seem to able to
get the following to ever deny any viruses:

#The following conditions don't work for aliasdomains (as the user isn't found!)
# Reject virus infested messages if user has virus=reject
  deny  message = This message contains malware ($malware_name). If you feel this isn't the case, please visit http://mail.$domain/malware
        malware = *
        condition = ${if eq{reject} {${lookup pgsql{SELECT virus FROM emailaccount WHERE emailaddress='${quote_pgsql:$local_part}@${quote_pgsql:$domain}'}}} {1} {0}}


But a simple
#The following conditions don't work for aliasdomains (as the user isn't found!)
# Reject virus infested messages if user has virus=reject
  deny  message = This message contains malware ($malware_name). If you feel this isn't the case, please visit http://mail.$domain/malware
        malware = *
        condition = ${if eq{reject} {reject} {1} {0}}

filters out my test virus (Gibe) without any trouble. So is it
possible that I can't access Postgre in this condition? Or are
local_part and domain not set at this stage? If so, is there even any
possibility to have different possibilities and still be able to drop
viruses before they hit the queue (well, obviously this means that
only one RCPT would be allowed at the time but in my tests I've used
one but admittedly not configured Exim to enforce this)?

I'd very much appreciate any comments on this matter.

TIA & regards,
Gabriel