received_header_text - what variables are available

After the discussion last week on $original_local_part and
$original_domain I thought it would be very useful if this info could be
put in the header, so I tried crafting my own received_header_text
config. Unfortunately, it doesn't seem like these variables are
available for that purpose. I tried the following..

received_header_text = "Received: \
          ${if def:sender_fullhost {from ${sender_fullhost} \
          ${if def:original_local_part {for $original_local_part} \
          ${if def:sender_ident {(${sender_ident})}}\n\t}\
          {${if def:sender_ident {from ${sender_ident} }}}}\
          by ${primary_hostname} \
          ${if def:received_protocol {with ${received_protocol}}} \
          (Exim ${version_number} #${compile_number})\n\t\
          id ${message_id}"

but just got errors from exim. The spec doesn't really mention what
variables are available for this besides the ones that are in the
default. The reason I would like to this is to be able to help identify
what mail address a mailing list or spammer is delivering mail to. Can
it be done?

-- 
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            GAT d- -p+(--) c++++ l++ u++ t- m--- W--- !v
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