Per-sender recipients blocklist

Hi.

I'm trying to implement per-sender recipients blocklist. In 
'acl_smtp_rcpt'
everything was quite simple:

         deny
             authenticated = *
             recipients = <, ${lookup {$sender_address} 
nwildlsearch{EXIM_DIR/recipients_blacklist}}
             message = Rejected by recipients blacklist

but for 'acl_not_smtp' such solution does not work. It's
tempting to do something like:

         discard
             set acl_m_recipients_blacklist = ${lookup {$sender_address} 
lsearch{EXIM_DIR/recipients_blacklist}}
             condition = ${if forany {<, $recipients} {match_address 
{$item}{<, $acl_m_recipients_blacklist}}}
             message = Rejected by recipients blacklist

but it doesn't work, because 'match_address' does not expand its second
argument. Neither does nested 'forany', because external '$item' is
overwritten and i don't have $item2:

             condition = ${if forany {<, $recipients} {
                                forany {<, $acl_m_recipients_blacklist}
                                    {match {$item}{$item2}}
                              }
                          }

The only working variant, which i can think of, is defining addresslist
externally and then using match_address on it, like:

         addresslist recipients_blacklist = <, ${lookup {$sender_address} 
lsearch{EXIM_DIR/recipients_blacklist}}
         acl_not_smtp = acl_check_not_smtp
         begin acl
             acl_check_not_smtp:
                 discard
                     condition = ${if forany {<, $recipients} 
{match_address {$item}{+recipients_blacklist}}}
                     message = Rejected by recipients blacklist

And indeed it works.

So, i have two questions:
- What is idiomatic way of searching an address in a list obtained from 
a lookup?
   (acl_smtp_rcpt case)
- And what is idiomatic way of checking whether any address (item?) from 
one list
   ($recipients) is part of the another (i.e. implementing nested loop
   essentially)? (acl_not_smtp case)

Thanks.

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