this sendmail error .. ??

[someone_4]

I have this sendmail error. Can someone tell me what it means? Does it mean that 207.46.142.135 is trying to use our sendmail server to relay spam? Does this mean that the anti-spam and closed relay are working correctly? Does this type of log message constantly show up in our sendmail logs? How secure is the current version of sendmail that we are using? Are there some security patches that need to be installed?
When nslookup on the IP address comes back to "lexiron.de.msn.com"

Apr 27 09:56:59 mail1 sendmail[25855]: JAA25855: Ruleset check_mail () rejection: 418 ... invalid host name
Apr 27 09:56:59 mail1 sendmail[25855]: JAA25855: from=, size=0, class=0, pri=0, nrcpts=0, proto=SMTP, relay=[207.46.142.135] (may be forged)
Apr 27 09:56:59 mail1 sendmail[25857]: JAA25857: Ruleset check_mail () rejection: 418 ... invalid host name
Apr 27 09:56:59 mail1 sendmail[25857]: JAA25857: from=, size=0, class=0, pri=0, nrcpts=0, proto=SMTP, relay=[207.46.142.135] (may be forged)
Apr 27 09:56:59 mail1 sendmail[25858]: JAA25858: Ruleset check_mail () rejection: 418 ... invalid host name
Apr 27 09:56:59 mail1 sendmail[25858]: JAA25858: from=, size=0, class=0, pri=0, nrcpts=0, proto=SMTP, relay=[207.46.142.135] (may be forged)

[someone_4]

We are running sendmail 8.8

[Kevin Wright · Accepted solution]

this message is a result of Sendmail perfoming a reverse DNS lookup of the domain msnnewsletters.msn.com. This domain does not exist, so you get the message that access was denied. Who is the message intended to reach? Since the relay is from msn, (lexiron.de)it seems like someone could be using that server as a relay to send spam out to internet hosts.Check your mail queue to ensure nothing is stuck in there, which will cause repeated error messages.
You should upgrade to sendmail 8.9.3.