Method of Operation (3)
ACLs

Introduced with version 4

May be applied at within the SMTP session
  acl_smtp_connect....ACL for start of SMTP connection
  acl_smtp_helo.......ACL for HELO or EHLO
  acl_smtp_starttls...ACL for STARTTLS
  acl_smtp_auth.......ACL for AUTH
  acl_smtp_mailauth...ACL for AUTH param of MAIL
  acl_smtp_mail.......ACL for MAIL
  acl_smtp_rcpt.......ACL for RCPT
  acl_smtp_data.......ACL after DATA