Имею при себе ubuntu 16.04 и там и там, postfix + sendmail без шифрования.
Postfix же работает как положено, а вот после переезда sendmail`а с centos на Ubuntu с аналогичной конфигруацией не работает.
Как настраивался Sendmail:
apt-get -y install sendmail
define(`MAIL_HUB',`[192.168.1.5]')dnl (в самый конец конфига(адрес postfix))
make -C /etc/mail
/etc/init.d/sendmail reload
Лог: mail.log
May 28 12:00:01 Web-Server sendmail[5756]: v4S901or005756: from=root, size=729, class=0, nrcpts=1, msgid=<201705280900.v4S901or005756@Web-Server>, bodytype=8BITMIME, relay=root@localhost
May 28 12:00:01 Web-Server sm-mta[5757]: v4S9013O005757: from=<root@Web-Server>, size=985, class=0, nrcpts=1, msgid=<201705280900.v4S901or005756@Web-Server>, bodytype=7BIT, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]
May 28 12:00:01 Web-Server sendmail[5756]: v4S901or005756: to=root, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30729, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (v4S9013O005757 Message accepted for delivery)
May 28 12:00:01 Web-Server sm-mta[5759]: STARTTLS=client, relay=[192.168.1.5], version=TLSv1.2, verify=FAIL, cipher=ECDHE-RSA-AES256-GCM-SHA384, bits=256/256
May 28 12:00:02 Web-Server sm-mta[5759]: v4S9013O005757: to=<root@Web-Server>, ctladdr=<root@Web-Server> (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=120985, relay=[192.168.1.5] [192.168.1.5], dsn=2.0.0, stat=Sent (Ok: queued as ECF6354002F)
Лог syslog:
May 28 12:00:01 Web-Server CRON[5731]: (root) CMD (test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(3600))' && certbot -q renew)
May 28 12:00:01 Web-Server CRON[5732]: (smmsp) CMD (test -x /etc/init.d/sendmail && test -x /usr/share/sendmail/sendmail && test -x /usr/lib/sm.bin/sendmail && /usr/share/sendmail/sendmail cron-msp)
May 28 12:00:01 Web-Server CRON[5733]: (root) CMD (certbot renew)
May 28 12:00:01 Web-Server sendmail[5756]: v4S901or005756: from=root, size=729, class=0, nrcpts=1, msgid=<201705280900.v4S901or005756@Web-Server>, bodytype=8BITMIME, relay=root@localhost
May 28 12:00:01 Web-Server sm-mta[5757]: v4S9013O005757: from=<root@Web-Server>, size=985, class=0, nrcpts=1, msgid=<201705280900.v4S901or005756@Web-Server>, bodytype=7BIT, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]
May 28 12:00:01 Web-Server sendmail[5756]: v4S901or005756: to=root, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30729, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (v4S9013O005757 Message accepted for delivery)
May 28 12:00:01 Web-Server sm-mta[5759]: STARTTLS=client, relay=[192.168.1.5], version=TLSv1.2, verify=FAIL, cipher=ECDHE-RSA-AES256-GCM-SHA384, bits=256/256
May 28 12:00:02 Web-Server sm-mta[5759]: v4S9013O005757: to=<root@Web-Server>, ctladdr=<root@Web-Server> (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=120985, relay=[192.168.1.5] [192.168.1.5], dsn=2.0.0, stat=Sent (Ok: queued as ECF6354002F)
cerbot сюда какого-то влез с Lets Encrypt'ом...