is my mail server open to relay???
 

As obvious I'm a Linux newbie and I've installed sendmail on my computer (redhat 8.0).

While browsing the maillog I've found the following:

Dec 7 17:10:09 mail sendmail[1810]: iB79A7sa001810: from=l815000@ddd.com, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, relay=[222.101.168.98]

Dec 11 18:52:12 mail sendmail[1511]: iBBAqCUN001511: es150.datareturn.com [216.46.246.233] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Dec 11 18:52:14 mail ipop3d[1512]: pop3 service init from 216.46.246.233
Dec 11 18:52:14 mail ipop3d[1512]: Command stream end of file while reading line user=??? host=port-216-3077865-es150.devices.datareturn.com [216.46.246.233]
Dec 11 19:26:08 mail sendmail[1963]: iBBBQ5UN001963: ruleset=check_rcpt, arg1=ssey1002@hanmail.net, relay=[222.101.168.98],
reject=550 5.7.1 ssey1002@hanmail.net... Relaying denied. IP name lookup failed [222.101.168.98]
Dec 11 19:26:08 mail sendmail[1963]: iBBBQ5UN001963: lost input channel from [222.101.168.98] to MTA after rcpt
Dec 11 19:26:08 mail sendmail[1963]: iBBBQ5UN001963: from=h317781@amazon.com, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, relay=[222.101.168.98]


It looks like that the hosts l815000@ddd.com and h317781@amazon.com could relay using my mail server.
I've runned an online open relay test and it failed saying that the server is not open to relay!

Thanks, Luca

It looks that your server has not accepted their connections.

Thanks I wasn't sure!

Luca,

As Mara pointed out your server doesn't appear to have accepted the connections (this is default behavior for Sendmail), but some online tests are more exhaustive than others (ordb.org has an excellent one).

You can see if your server is a relay via this test. From a command line on the server, run:

It will run several different relay attempts, and give you a report.

-Corey

I've tested it and it is not open to relay :D

Thanks all for your kind support!!!