[Exim] Alias

Hi!

Is it possible to change the 'to:' address in a mail header to the new
aliased address? So if a mail is sent to address a@??? and a@???
is an alias for

name@??? to change the 'to:' header in the mail to name@????

I've been searching to headers_remove and headers_add, this seems to work
fine, the problem I'm having is where can I get the result of an aliasfile
lookup? Is it in any variable? And at what time is it in that variable? Are
the headers_remove/add done after the query in a director?

This is what I got :

test_director:
driver = aliasfile
domains = test.com
search_type = mysql
query = "select mail from aliases where list_id=2 and
'${quote_mysql:$local_part}' = 'blub'" # return multiple addresses
# headers_remove = to:
# headers_add = "to: <>"
debug_print = $original_local_part $local_part $parent_local_part
$reply_address $return_path $sender_address # none of these hold the new
aliased address

Thanks for any clues!

EG