Hi wraptor, I am using Ubuntu 16.04,
Here is my mail.log file
"Aug 4 03:30:02 mail postfix/pickup[32141]: 99BB245A44: uid=0 from=<root>
Aug 4 03:30:02 mail postfix/cleanup[667]: 99BB245A44: message-id=<20180804033002.99BB245A44@mail.marketingleomail.ml>
Aug 4 03:30:02 mail postfix/qmgr[4404]: 99BB245A44: from=<root@mail.marketingleomail.ml>, size=1241, nrcpt=1 (queue active)
Aug 4 03:30:03 mail postfix/10025/smtpd[681]: connect from mail.marketingleomail.ml[127.0.0.1]
Aug 4 03:30:03 mail postfix/10025/smtpd[681]: 3FB5245A42: client=mail.marketingleomail.ml[127.0.0.1]
Aug 4 03:30:03 mail postfix/cleanup[667]: 3FB5245A42: message-id=<20180804033002.99BB245A44@mail.marketingleomail.ml>
Aug 4 03:30:03 mail postfix/qmgr[4404]: 3FB5245A42: from=<root@mail.marketingleomail.ml>, size=1784, nrcpt=1 (queue active)
Aug 4 03:30:03 mail postfix/10025/smtpd[681]: disconnect from mail.marketingleomail.ml[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Aug 4 03:30:03 mail amavis[2665]: (02665-01) Passed CLEAN {RelayedInbound}, [127.0.0.1] <root@mail.marketingleomail.ml> -> <root@mail.marketingleomail.ml>, Message-ID: <20180804033002.99BB245A44@mail.marketingleomail.ml>, mail_id: R5cWaIp0DbgW, Hits: 0, size: 1241, queued_as: 3FB5245A42, 490 ms, Tests: [NO_RELAYS=-0.001,TVD_SPACE_RATIO=0.001]
Aug 4 03:30:03 mail postfix/amavis/smtp[675]: 99BB245A44: to=<root@mail.marketingleomail.ml>, relay=127.0.0.1[127.0.0.1]:10024, delay=0.74, delays=0.16/0.08/0.01/0.49, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 3FB5245A42)
Aug 4 03:30:03 mail postfix/qmgr[4404]: 99BB245A44: removed
Aug 4 03:30:03 mail postfix/cleanup[667]: 481A445A44: message-id=<20180804033002.99BB245A44@mail.marketingleomail.ml>
Aug 4 03:30:03 mail postfix/qmgr[4404]: 481A445A44: from=<root@mail.marketingleomail.ml>, size=1933, nrcpt=1 (queue active)
Aug 4 03:30:03 mail postfix/local[684]: 3FB5245A42: to=<root@mail.marketingleomail.ml>, relay=local, delay=0.04, delays=0.01/0.02/0/0.02, dsn=2.0.0, status=sent (forwarded as 481A445A44)
Aug 4 03:30:03 mail postfix/qmgr[4404]: 3FB5245A42: removed
Aug 4 03:30:03 mail postfix/pipe[686]: 481A445A44: to=<postmaster@marketingleomail.ml>, relay=dovecot, delay=0.12, delays=0/0.01/0/0.1, dsn=2.0.0, status=sent (delivered via dovecot service)
Aug 4 03:30:03 mail postfix/qmgr[4404]: 481A445A44: removed
Aug 4 06:25:04 mail postfix/pickup[4967]: 7AD8245A42: uid=0 from=<root>
Aug 4 06:25:04 mail postfix/cleanup[5462]: 7AD8245A42: message-id=<20180804062504.7AD8245A42@mail.marketingleomail.ml>
Aug 4 06:25:04 mail postfix/qmgr[4404]: 7AD8245A42: from=<root@mail.marketingleomail.ml>, size=38225, nrcpt=1 (queue active)
Aug 4 06:25:06 mail postfix/10025/smtpd[5603]: connect from mail.marketingleomail.ml[127.0.0.1]
Aug 4 06:25:06 mail postfix/10025/smtpd[5603]: 4215445A44: client=mail.marketingleomail.ml[127.0.0.1]
Aug 4 06:25:06 mail postfix/cleanup[5462]: 4215445A44: message-id=<20180804062504.7AD8245A42@mail.marketingleomail.ml>
Aug 4 06:25:06 mail postfix/qmgr[4404]: 4215445A44: from=<root@mail.marketingleomail.ml>, size=38768, nrcpt=1 (queue active)
Aug 4 06:25:06 mail postfix/10025/smtpd[5603]: disconnect from mail.marketingleomail.ml[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Aug 4 06:25:06 mail amavis[2666]: (02666-01) Passed CLEAN {RelayedInbound}, [127.0.0.1] <root@mail.marketingleomail.ml> -> <root@mail.marketingleomail.ml>, Message-ID: <20180804062504.7AD8245A42@mail.marketingleomail.ml>, mail_id: FLJUhg1Vl15z, Hits: -0.001, size: 38217, queued_as: 4215445A44, 1744 ms, Tests: [NO_RELAYS=-0.001]
Aug 4 06:25:06 mail postfix/amavis/smtp[5479]: 7AD8245A42: to=<root@mail.marketingleomail.ml>, relay=127.0.0.1[127.0.0.1]:10024, delay=3.5, delays=1.7/0.01/0.01/1.7, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 4215445A44)
Aug 4 06:25:06 mail postfix/qmgr[4404]: 7AD8245A42: removed
Aug 4 06:25:06 mail postfix/cleanup[5462]: 4A20745A42: message-id=<20180804062504.7AD8245A42@mail.marketingleomail.ml>
Aug 4 06:25:06 mail postfix/qmgr[4404]: 4A20745A42: from=<root@mail.marketingleomail.ml>, size=38917, nrcpt=1 (queue active)
Aug 4 06:25:06 mail postfix/local[5604]: 4215445A44: to=<root@mail.marketingleomail.ml>, relay=local, delay=0.04, delays=0.01/0.02/0/0.02, dsn=2.0.0, status=sent (forwarded as 4A20745A42)
Aug 4 06:25:06 mail postfix/qmgr[4404]: 4215445A44: removed
Aug 4 06:25:06 mail postfix/pipe[5606]: 4A20745A42: to=<postmaster@marketingleomail.ml>, relay=dovecot, delay=0.06, delays=0/0.01/0/0.05, dsn=2.0.0, status=sent (delivered via dovecot service)
Aug 4 06:25:06 mail postfix/qmgr[4404]: 4A20745A42: removed
Aug 4 06:29:11 mail postfix/postscreen[5755]: CONNECT from [141.212.122.208]:52243 to [172.31.5.74]:25
Aug 4 06:29:11 mail postfix/postscreen[5755]: cache btree:/var/lib/postfix/postscreen_cache full cleanup: retained=3 dropped=0 entries
Aug 4 06:29:15 mail postfix/postscreen[5755]: HANGUP after 4.7 from [141.212.122.208]:52243 in tests before SMTP handshake
Aug 4 06:29:15 mail postfix/postscreen[5755]: DISCONNECT [141.212.122.208]:52243
Aug 4 07:01:58 mail amavis[7137]: starting. /usr/sbin/amavisd-new at mail.marketingleomail.ml amavisd-new-2.10.1 (20141025), Unicode aware, LC_ALL="C", LANG="en_US.UTF-8"
Aug 4 07:01:58 mail amavis[7145]: Net::Server: Group Not Defined. Defaulting to EGID '124 124'
Aug 4 07:01:58 mail amavis[7145]: Net::Server: User Not Defined. Defaulting to EUID '118'
Aug 4 07:01:58 mail amavis[7145]: Module Amavis::Conf 2.404
Aug 4 07:01:58 mail amavis[7145]: Module Archive::Zip 1.56
Aug 4 07:01:58 mail amavis[7145]: Module Compress::Raw::Zlib 2.068
Aug 4 07:01:58 mail amavis[7145]: Module Compress::Zlib 2.068
Aug 4 07:01:58 mail amavis[7145]: Module Crypt::OpenSSL::RSA 0.28
Aug 4 07:01:58 mail amavis[7145]: Module DBD::mysql 4.033
Aug 4 07:01:58 mail amavis[7145]: Module DBI 1.634
Aug 4 07:01:58 mail amavis[7145]: Module DB_File 1.835
Aug 4 07:01:58 mail amavis[7145]: Module Digest::MD5 2.54
Aug 4 07:01:58 mail amavis[7145]: Module Digest::SHA 5.95
Aug 4 07:01:58 mail amavis[7145]: Module Encode 2.72
Aug 4 07:01:58 mail amavis[7145]: Module File::Temp 0.2304
Aug 4 07:01:58 mail amavis[7145]: Module IO::Socket::INET6 2.72
Aug 4 07:01:58 mail amavis[7145]: Module IO::Socket::IP 0.37
Aug 4 07:01:58 mail amavis[7145]: Module MIME::Entity 5.507
Aug 4 07:01:58 mail amavis[7145]: Module MIME::Parser 5.507
Aug 4 07:01:58 mail amavis[7145]: Module MIME::Tools 5.507
Aug 4 07:01:58 mail amavis[7145]: Module Mail::DKIM::Signer 0.4
Aug 4 07:01:58 mail amavis[7145]: Module Mail::DKIM::Verifier 0.4
Aug 4 07:01:58 mail amavis[7145]: Module Mail::Header 2.13
Aug 4 07:01:58 mail amavis[7145]: Module Mail::Internet 2.13
Aug 4 07:01:58 mail amavis[7145]: Module Mail::SPF v2.009
Aug 4 07:01:58 mail amavis[7145]: Module Mail::SpamAssassin 3.004001
Aug 4 07:01:58 mail amavis[7145]: Module Net::DNS 0.81
Aug 4 07:01:58 mail amavis[7145]: Module Net::LibIDN 0.12
Aug 4 07:01:58 mail amavis[7145]: Module Net::Server 2.008
Aug 4 07:01:58 mail amavis[7145]: Module NetAddr::IP 4.078
Aug 4 07:01:58 mail amavis[7145]: Module Scalar::Util 1.41
Aug 4 07:01:58 mail amavis[7145]: Module Socket 2.018
Aug 4 07:01:58 mail amavis[7145]: Module Socket6 0.25
Aug 4 07:01:58 mail amavis[7145]: Module Time::HiRes 1.9726
Aug 4 07:01:58 mail amavis[7145]: Module URI 1.71
Aug 4 07:01:58 mail amavis[7145]: Module Unix::Syslog 1.1
Aug 4 07:01:58 mail amavis[7145]: Amavis::ZMQ code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: Amavis::DB code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: SQL base code loaded
Aug 4 07:01:58 mail amavis[7145]: SQL::Log code loaded
Aug 4 07:01:58 mail amavis[7145]: SQL::Quarantine loaded
Aug 4 07:01:58 mail amavis[7145]: Lookup::SQL code loaded
Aug 4 07:01:58 mail amavis[7145]: Lookup::LDAP code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: AM.PDP-in proto code loaded
Aug 4 07:01:58 mail amavis[7145]: SMTP-in proto code loaded
Aug 4 07:01:58 mail amavis[7145]: Courier proto code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: SMTP-out proto code loaded
Aug 4 07:01:58 mail amavis[7145]: Pipe-out proto code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: BSMTP-out proto code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: Local-out proto code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: OS_Fingerprint code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: ANTI-VIRUS code loaded
Aug 4 07:01:58 mail amavis[7145]: ANTI-SPAM code loaded
Aug 4 07:01:58 mail amavis[7145]: ANTI-SPAM-EXT code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: ANTI-SPAM-C code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: ANTI-SPAM-SA code loaded
Aug 4 07:01:58 mail amavis[7145]: Unpackers code loaded
Aug 4 07:01:58 mail amavis[7145]: DKIM code loaded
Aug 4 07:01:58 mail amavis[7145]: Tools code NOT loaded
Aug 4 07:01:58 mail amavis[7145]: Found $file at /usr/bin/file
Aug 4 07:01:58 mail amavis[7145]: Found $altermime at /usr/bin/altermime
Aug 4 07:01:58 mail amavis[7145]: Internal decoder for .mail
Aug 4 07:01:58 mail amavis[7145]: No ext program for .F, tried: unfreeze, freeze -d, melt, fcat
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .Z at /bin/uncompress
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .gz at /bin/gzip -d
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .bz2 at /bin/bzip2 -d
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .xz at /usr/bin/xz -dc
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .lzma at /usr/bin/xz -dc --format=lzma
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .lrz at /usr/bin/lrzip -q -k -d -o -
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .lzo at /usr/bin/lzop -d
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .lz4 at /usr/bin/lz4c -d
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .rpm at /usr/bin/rpm2cpio
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .cpio at /bin/pax
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .tar at /bin/pax
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .deb at /usr/bin/ar
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .rar at /usr/bin/unrar
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .arj at /usr/bin/arj
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .arc at /usr/bin/nomarch
Aug 4 07:01:58 mail amavis[7145]: No ext program for .zoo, tried: zoo, unzoo
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .cab at /usr/bin/cabextract
Aug 4 07:01:58 mail amavis[7145]: Internal decoder for .tnef
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .zip at /usr/bin/7za
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .kmz at /usr/bin/7za
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .7z at /usr/bin/7za
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .jar at /usr/bin/7z
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .swf at /usr/bin/7z
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .lha at /usr/bin/7z
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .iso at /usr/bin/7z
Aug 4 07:01:58 mail amavis[7145]: Found decoder for .exe at /usr/bin/unrar; /usr/bin/arj
Aug 4 07:01:58 mail amavis[7145]: No decoder for .F
Aug 4 07:01:58 mail amavis[7145]: No decoder for .zoo
Aug 4 07:01:58 mail amavis[7145]: Using primary internal av scanner code for clamav-socket
Aug 4 07:01:58 mail amavis[7145]: Found secondary av scanner clamav-clamscan at /usr/bin/clamscan
Aug 4 14:54:30 mail postfix/postscreen[19085]: CONNECT from [41.212.69.205]:56466 to [172.31.5.74]:25
Aug 4 14:54:30 mail postfix/postscreen[19085]: HANGUP after 0 from [41.212.69.205]:56466 in tests before SMTP handshake
Aug 4 14:54:30 mail postfix/postscreen[19085]: DISCONNECT [41.212.69.205]:56466
Aug 4 14:54:30 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.4
Aug 4 14:54:30 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 4 14:54:30 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain b.barracudacentral.org as 127.0.0.2
Aug 4 14:54:30 mail postfix/postscreen[19085]: CONNECT from [41.212.69.205]:56493 to [172.31.5.74]:25
Aug 4 14:54:30 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 4 14:54:30 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.4
Aug 4 14:54:30 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain b.barracudacentral.org as 127.0.0.2
Aug 4 14:54:36 mail postfix/postscreen[19085]: DNSBL rank 5 for [41.212.69.205]:56493
Aug 4 14:54:36 mail postfix/postscreen[19085]: DISCONNECT [41.212.69.205]:56493
Aug 4 14:54:37 mail postfix/postscreen[19085]: CONNECT from [41.212.69.205]:57168 to [172.31.5.74]:25
Aug 4 14:54:37 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain b.barracudacentral.org as 127.0.0.2
Aug 4 14:54:37 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.4
Aug 4 14:54:37 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 4 14:54:43 mail postfix/postscreen[19085]: DNSBL rank 5 for [41.212.69.205]:57168
Aug 4 14:54:43 mail postfix/postscreen[19085]: DISCONNECT [41.212.69.205]:57168
Aug 4 14:54:44 mail postfix/postscreen[19085]: CONNECT from [41.212.69.205]:57461 to [172.31.5.74]:25
Aug 4 14:54:44 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain b.barracudacentral.org as 127.0.0.2
Aug 4 14:54:44 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 4 14:54:44 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.4
Aug 4 14:54:50 mail postfix/postscreen[19085]: DNSBL rank 5 for [41.212.69.205]:57461
Aug 4 14:54:50 mail postfix/postscreen[19085]: DISCONNECT [41.212.69.205]:57461
Aug 4 14:54:50 mail postfix/postscreen[19085]: CONNECT from [41.212.69.205]:57651 to [172.31.5.74]:25
Aug 4 14:54:50 mail postfix/dnsblog[19086]: addr 41.212.69.205 listed by domain b.barracudacentral.org as 127.0.0.2
Aug 4 14:54:50 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.4
Aug 4 14:54:50 mail postfix/dnsblog[19087]: addr 41.212.69.205 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 4 14:54:56 mail postfix/postscreen[19085]: DNSBL rank 5 for [41.212.69.205]:57651
Aug 4 14:54:56 mail postfix/postscreen[19085]: DISCONNECT [41.212.69.205]:57651
"