$ grep 'blackhole' /var/log/maillog | grep jp Nov 22 22:07:29 mail sendmail[82950]: eAMD7Ss82950: ruleset=check_relay, arg1=XX XXXXXX.XXXXXXX.XXX.ne.jp, arg2=210.162.XXX.XXX, relay=XXXXXXXX.XXXXXXX.XXXX .XXX.ne.jp [210.162.XXX.XXX], reject=550 5.7.1 Mail from 210.162.XXX.XXX refused by blackhole site relays.orbs.org