[Exim] long time before getting 550 User unknown

I can't figure why my Exim server takes about 10 or 15 seconds to
return my a "550 User unknown" error when sending email with a not
valid local part...

here's my last router :

mysql_user:
   driver = accept
   condition = ${if eq{} {${lookup mysql {SELECT home FROM passwd \
                 WHERE id="${local_part}@${domain}"}}} {no}{yes}}
   retry_use_local_part
   transport=mysql_delivery

should I add something in the router?

should I add another router after this one?

thanks


Dominic Germain
---------------------------------------------
Administrateur réseau / Network administrator
Internet Galilée

network-admin@???
1-800-561-3703 x226