Re: [exim] How do ISP's restrict access without authenticati…

This is the check we are doing:

In the mail ACL we do a database query using the value $sender_host_address

    deny 
      set acl_m1 = ${lookup pgsql{ select smtp_identify_user( \
      '${quote_pgsql:$authenticated_id}',\
      '${quote_pgsql:$sender_address}',\
      '${quote_pgsql:$sender_host_address}'\
       )}{$value}}
       Message =  ${substr_3:$acl_m1} 
       condition = ${if eq {${substr_0_3:$acl_m1}}{X: }}
     defer
       message =  ${substr_3:$acl_m1} 
       condition = ${if eq {${substr_0_3:$acl_m1}}{Y: }}
     accept
       condition = ${if gt{${substr_0_3:$acl_m1}}{A: }}

we then choose to accept or defer depending on what we get.