[Exim] Recipients lookup

Hi all,

i'm verifying recipients via LDAP with this director:

local_not_exist:
         condition = "${lookup ldap
{ldap:///c=IT?mail?sub?(&(shortname=$local_part))}{0}{1}}"
   driver = smartuser
   transport = rcpt_not_found_autoreply

This runs great but i wish to verify recipients during smpt dialogue (after
RCPT TO commands) and not after i've accepted mails.

Is it possible?

Thank you,

Riccardo