open relay test discrepancy


nmap smtp open relay test shows (verbose mode):

smtp-open-relay: Server is an open relay (5/16 tests)   MAIL FROM:<antispam@[xxx.xxx.xx.xx]> -> RCPT TO:<relaytest%nmap.scanme.org@XHS5P>   MAIL FROM:<antispam@[xxx.xxx.xx.xx]> -> RCPT TO:<"relaytest@nmap.scanme.org">   MAIL FROM:<antispam@[xxx.xxx.xx.xx]> -> RCPT TO:<"relaytest%nmap.scanme.org">   MAIL FROM:<antispam@[xxx.xxx.xx.xx]> -> RCPT TO:<nmap.scanme.org!relaytest>   MAIL FROM:<antispam@[xxx.xxx.xx.xx]> -> RCPT TO:<nmap.scanme.org!relaytest@XHS5P> 

xxx.xxx.xx.xx being host IP smtp: Microsoft ESMTP 6.0.2600.5949

Previous tests through mxtoolbox:

MAIL FROM:<supertool@mxtoolbox.com> 250 2.1.0 supertool@mxtoolbox.com....Sender OK [703 ms] RCPT TO:<test@mxtoolboxsmtpdiag.com> 550 5.7.1 Unable to relay for test@mxtoolboxsmtpdiag.com [696 ms] 

According to mxtoolbox, my host is not an open relay smtp

My question:

  • can I consider nmap test unreliable?

In order to check, nmap results I made a few test myself using nmap output

Here’s what I got:

HELO 250 XHS5P Hello [yy.yy.yyy.yyy] MAIL FROM:<tester@bogusyyyyyw.com> 250 2.1.0 tester@bogusyyyyyw.com....Sender OK RCPT TO:<"relaytest@nmap.scanme.org"> 250 2.1.5 "relaytest@nmap.scanme.org"@XHS5P 

status code 250 2.1.5 means: email has been delivered

So, nmap was right. But I still believe it was not, since perhaps it has to do with the the fact that the recipient has double quotes

Can someone help me to figure out if my host is an open relay?

thanks a lot