AclSmtpRcpt

RCPT ACL

Bounces are never sent to more than one recipient.

drop    message = Legitimate bounces are never sent to more than one recipient.
        senders = : postmaster@*
        condition = ${if >{$recipients_count}{0}{true}{false}}

Drop if more than 3 bad recipients.

drop    message = REJECTED - Too many failed recipients - count = $rcpt_fail_count
        log_message = REJECTED - Too many failed recipients - count = $rcpt_fail_count
        condition = ${if > {${eval:$rcpt_fail_count}}{3}{yes}{no}}
        condition = ${run{/etc/exim/scripts/log-file /var/spool/spam/host-spam.txt $sender_host_address}{yes}{yes}}
        !verify = recipient/callout=2m,defer_ok,use_sender

Drop if any of the recipients mentioned is one which only ever receives spam (ideally, a spam "trap" address):

drop    condition = ${lookup{$local_part@$domain}lsearch{/etc/exim/only-used-by-spammers} {yes}{no}}
        logwrite = :main,reject: $sender_host_address - $local_part@$domain is only used by spammers
        message = I don't think so

Suggestions for improving the condition welcomed - e.g. maybe use match_address?

Drop if destination is myprotecteddomain.com or my2protecteddomain.com but source is not *myowndomain.com . It will log useful info in exim log and only give administration prohibited to the other mta. Great for domains you know sources. (generaly internal use domain) :

deny       log_message =  $sender_address is not permitted to send to myprotecteddomain.com my2protecteddomain.com
           domains     = myprotecteddomain.com : my2protecteddomain.com
           ! senders   = *myowndomain.com