Feb 21 10:48:32 my-hostname sm-mta[5722]: to=<existing_email_address@gmail.com>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=154468, relay=gmail-smtp-in.l.google.com. [108.177.119.27], dsn=2.0.0, stat=Sent (OK  1550746112 j9si7086675ede.335 - gsmtp)

Feb 21 10:26:39 my-hostname sm-mta[5293]: to=<test-xxxxx@mail-tester.com>, delay=00:00:02, xdelay=00:00:01, mailer=esmtp, pri=153623, relay=mail-tester.com. [94.23.206.89], dsn=2.0.0, stat=Sent (Ok: queued as 166399F70A)

Feb 21 10:40:49 my-hostname sm-mta[5634]: to=<existing_email_address@hotmail.com>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=154470, relay=hotmail-com.olc.protection.outlook.com. [104.47.0.33], dsn=5.0.0, stat=Service unavailable

Feb 21 10:50:14 my-hostname sm-mta[5727]: to=<existing_email_address@random-existing-domain.com>, delay=00:00:06, xdelay=00:00:06, mailer=esmtp, pri=154475, relay=random-existing-domain [xxx.xx.xxx.x], dsn=5.1.1, stat=User unknown