[Exim] data in a transport

If I understand correctly, in the Routers area of the config file
data = ${lookup mysql{Select user, group, maildir from passwd where
email='{$1}'}{$value}}

sets the values for user, group and maildir to the values pulled from the
database.

Can this be done in the Transports area as well? If so, how? The above
statement causes Exim 4.05 not to start with a 'data unknown' error:

Relevant portions of the config file:

begin transports
mysql_delivery:
  driver = appendfile
  maildir_format
  data = ${lookup mysql{SELECT_USER_FOR_DELIVERY}{$value}}
  mode               = 0660
  mode_fail_narrower = false
  envelope_to_add    = true
  return_path_add    = true
  create_directory   = true

TIA,
=C=
*
* Cal Evans
* The Virtual CIO
* http://www.calevans.com
*