Here one with more detail:
Dec 16 16:34:40 mail postfix/smtp[18468]: 20110B2FE5: host mx3.hanmail.net[211.110.65.14] refused to talk to me: 554 5.7.1 CCRX 173.255.237.18: Connection refused. Your IP address is blocked(anti-spam). If you need, please contact
hanmailcs@daumcorp.com.
Dec 16 16:34:40 mail postfix/smtp[18525]: 687C1B3278: to=<shome41@bigpond.com>, relay=extmail.bigpond.com[61.9.189.122]:25, delay=934, delays=933/0.23/0.93/0, dsn=4.0.0, status=deferred (host extmail.bigpond.com[61.9.189.122] refused to talk to me: 554 nschwcmgw04p BigPond Inbound IB104b. Connection refused. 173.255.237.18 is listed on the Exploits Block List (XBL). Please visit
http://www.spamhaus.org/xbl/ for more information.)
Dec 16 16:34:40 mail postfix/smtp[18495]: 3824A240FC: to=<security@myserver.com>, relay=ALT1.ASPMX.L.GOOGLE.com[64.233.190.26]:25, delay=542, delays=541/0.31/0.99/0.34, dsn=4.2.1, status=deferred (host ALT1.ASPMX.L.GOOGLE.com[64.233.190.26] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1
https://support.google.com/mail/answer/6592 r85si6370981vke.56 - gsmtp (in reply to RCPT TO command))
Dec 16 16:34:40 mail postfix/smtp[18510]: BCD60B3319: host mx.vgs.untd.com[64.136.52.37] refused to talk to me: 550 IP 173.255.237.18 in zen.spamhaus.org : Access Denied, please see
www.spamhaus.org Dec 16 16:34:40 mail postfix/smtp[18509]: B2440B2C43: to=<security@myserver.com>, relay=ALT1.ASPMX.L.GOOGLE.com[64.233.190.26]:25, delay=1169, delays=1167/0.34/0.9/0.31, dsn=4.2.1, status=deferred (host ALT1.ASPMX.L.GOOGLE.com[64.233.190.26] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1
https://support.google.com/mail/answer/6592 p21si6372161vke.80 - gsmtp (in reply to RCPT TO command))
Dec 16 16:34:40 mail postfix/smtp[18473]: EFC79B332E: to=<sydpat22@yahoo.com.au>, relay=mta7.am0.yahoodns.net[98.136.217.202]:25, delay=585, delays=583/0.13/0.94/0.07, dsn=4.7.0, status=deferred (host mta7.am0.yahoodns.net[98.136.217.202] said: 421 4.7.0 [TS01] Messages from 173.255.237.18 temporarily deferred due to user complaints - 4.16.55.1; see
https://help.yahoo.com/kb/postmaster/SLN3434.html (in reply to MAIL FROM command))
Dec 16 16:34:40 mail postfix/smtp[18493]: E1446B3340: to=<simba38@bigpond.com>, relay=extmail.bigpond.com[61.9.189.122]:25, delay=911, delays=909/0.22/0.92/0, dsn=4.0.0, status=deferred (host extmail.bigpond.com[61.9.189.122] refused to talk to me: 554 nschwcmgw04p BigPond Inbound IB104b. Connection refused. 173.255.237.18 is listed on the Exploits Block List (XBL). Please visit
http://www.spamhaus.org/xbl/ for more information.)
Dec 16 16:34:40 mail postfix/smtp[18459]: 8B251B3192: host mx.east.cox.net[68.1.17.3] refused to talk to me: 554 eastrmimpi211 cox 173.255.237.18 blocked. Error Code: IPBL0001 - Refer to Error Codes section at
http://postmaster.cox.net/confluence/di ... rror+Codes for more information.
Dec 16 16:34:40 mail postfix/smtp[18476]: DE73E2414F: to=<tengjw@singnet.com.sg>, relay=mx-fuse-1.singnet.com.sg[202.40.249.79]:25, delay=428, delays=426/0.15/1.1/0, dsn=4.0.0, status=deferred (host mx-fuse-1.singnet.com.sg[202.40.249.79] refused to talk to me: 520 Blacklisted)
Dec 16 16:34:40 mail postfix/smtp[18483]: 74D60B3289: to=<shome@libpac.com>, relay=alt1.aspmx.l.google.com[64.233.190.26]:25, delay=934, delays=933/0.33/0.88/0.29, dsn=4.2.1, status=deferred (host alt1.aspmx.l.google.com[64.233.190.26] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1
https://support.google.com/mail/answer/6592 7si6372954vkj.74 - gsmtp (in reply to RCPT TO command))
Dec 16 16:34:40 mail postfix/smtp[18479]: 7228824186: to=<torun.tysse.landsvik@nordea.com>, relay=cluster4a.eu.messagelabs.com[85.158.139.103]:25, delay=354, delays=353/0.33/1.1/0.1, dsn=4.0.0, status=deferred (host cluster4a.eu.messagelabs.com[85.158.139.103] said: 421 Service Temporarily Unavailable (in reply to RCPT TO command))
Dec 16 16:34:40 mail postfix/smtp[18512]: 1F2FFB325F: to=<security@myserver.com>, relay=ALT1.ASPMX.L.GOOGLE.com[64.233.190.26]:25, delay=938, delays=936/0.35/0.98/0.37, dsn=4.2.1, status=deferred (host ALT1.ASPMX.L.GOOGLE.com[64.233.190.26] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1
https://support.google.com/mail/answer/6592 195si6353668vkg.117 - gsmtp (in reply to RCPT TO command))
Dec 16 16:34:40 mail postfix/smtp[18457]: CAE74B331B: to=<sydowprop@telkomsa.net>, relay=mx2.telkomsa.net[196.25.211.172]:25, delay=585, delays=583/0.3/1.5/0, dsn=4.0.0, status=deferred (host mx2.telkomsa.net[196.25.211.172] refused to talk to me: 554-as5.telkomsa.net 554 Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means.)
Dec 16 16:34:40 mail postfix/smtp[18468]: 20110B2FE5: to=<sbgshin@daum.net>, relay=mx2.hanmail.net[180.70.93.97]:25, delay=1023, delays=1021/0.2/2/0, dsn=4.7.1, status=deferred (host mx2.hanmail.net[180.70.93.97] refused to talk to me: 554 5.7.1 CCRX 173.255.237.18: Connection refused. Your IP address is blocked(anti-spam). If you need, please contact
hanmailcs@daumcorp.com.)
Dec 16 16:34:40 mail postfix/smtp[18507]: B9238B2D4E: to=<sanpietro9@vodafone.it>, relay=mx.vodafone.arubamail.it[62.149.178.10]:25, delay=1141, delays=1139/0.33/1.7/0, dsn=4.0.0, status=deferred (host mx.vodafone.arubamail.it[62.149.178.10] refused to talk to me: 554 mxcmd02.vf.aruba.it bizsmtp uGaf1r0040QWJit01 Connection refused from 173.255.237.18. See
http://www.spamhaus.org/query/bl?ip=173.255.237.18 for more information.)
Dec 16 16:34:40 mail postfix/smtp[18494]: 3D125241A3: to=<torus@comcast.net>, relay=mx1.comcast.net[96.114.157.80]:25, delay=330, delays=328/0.3/1.9/0, dsn=4.0.0, status=deferred (host mx1.comcast.net[96.114.157.80] refused to talk to me: 554 resimta-po-20v.sys.comcast.net comcast 173.255.237.18 found on one or more DNSBLs, see
http://postmaster.comcast.net/smtp-erro ... p#BL000001)
Dec 16 16:34:41 mail postfix/smtp[18510]: BCD60B3319: to=<shomeraz@juno.com>, relay=mx.dca.untd.com[64.136.44.37]:25, delay=920, delays=917/0.36/2.2/0, dsn=4.0.0, status=deferred (host mx.dca.untd.com[64.136.44.37] refused to talk to me: 550 IP 173.255.237.18 in zen.spamhaus.org : Access Denied, please see
www.spamhaus.org )
Dec 16 16:34:41 mail postfix/smtp[18459]: 8B251B3192: to=<shaut@cox.net>, relay=mx.west.cox.net[68.6.19.3]:25, delay=978, delays=976/0.31/2.3/0, dsn=4.0.0, status=deferred (host mx.west.cox.net[