[exim] Drop failed authenticated users as quickly as I can

I want to implement a control on my mail server to drop failed authenticated
users as quickly as I can.

Actually, my configure file look like as:

...

acl_smtp_auth = smtp_auth
acl_smtp_rcpt = check_rcpt
acl_smtp_data = check_spam
...

begin acl

smtp_auth:
accept


check_rcpt:
accept authenticated = fixed_login

  accept  condition     = ${perl{check_deliver}{$domain}{$local_part}}

  accept  condition     = ${perl{checkvalias}{$domain}{$local_part}}

  deny    message = User unknown

check_spam:
  warn
 condition = ${if <{$message_size}{SPAM_CHK_MAXSIZE}{1}{0}}
 message = X-Spam-Score-Int: $spam_score_int
    spam = nobody:true/defer_ok

  deny
     condition = ${if >{$spam_score_int}{SPAM_SCOREINT_TO_DISCARD}{1}{0}}
     message   = Our mail system has determined your message to be SPAM.
     spam = nobody:true

accept


begin authenticators

fixed_login:
driver = plaintext
public_name = LOGIN
server_prompts = "Username:: : Password::"
server_condition = "${perl{checkuserpass}{$auth1}{$auth2}}"
server_set_id = $auth1



I thinks that where I made the check to authenticated at check_rcpt it's
wrong. It's this really wrong?

If it's wrong, where I may does the control? At smtp_auth (acl_smtp_auth)
section?

It may be this way?

smtp_auth:
drop !authenticated = fixed_login

accept

check_rcpt:
  accept  condition     = ${perl{check_deliver}{$domain}{$local_part}}

  accept  condition     = ${perl{checkvalias}{$domain}{$local_part}}

  deny    message = User unknown

An if this approach is correct, when drop at smtp_auth section, Exim
immediately exit? or it does the remaining controls?

Can anyone help me?

Thanks in advance.

Jorge Colaccini