(April 2002)
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Majordomo-Users (April 2002) |
karlp@ourldsfamily.com wanted us to know: >No, I don't have an open relay host. If you want to check it out, it's my >own host and my own domain. NMAP doesn't even return anything on it, if >that helps. Along a different line, many sites use another method of spam prevention. If the IP address of your mail server does not reverse resolve, they will bounce your mail. What is the external IP address of your mail server? As an example, I have a domain mrball.net. Mail originates from my mail server and it says "somebody@mrball.net". The receiving mail server first checks to see if mrball.net is a valid domain by asking a domain name server. In my case, the answer will be: [todd@todd ~/.netscape]$ host mrball.net 4.2.2.1 Using domain server 4.2.2.1: mrball.net has address 24.205.75.223 mrball.net mail is handled (pri=10) by mrball.net mrball.net mail is handled (pri=20) by northeast-loans.com If it gets an answer back, then (a new thing) the second check is to do the reverse IP. In my case: [todd@todd ~/.netscape]$ host 24.205.75.223 4.2.2.1 Using domain server 4.2.2.1: 223.75.205.24.IN-ADDR.ARPA domain name pointer 24-205-75-223.glen-dyn.charterpipeline.net Since it reverse resolves to something, it decides to accept the mail. Notice that it doesn't resolve to the same name as the original name. In most cases that doesn't matter. If it _did_ matter, then virtual hosting would not be possible as one mail server can host multiple domains, but many people do not know how to make a nameserver reverse resolve more than one name for a single IP (though it's pretty damn simple :) Also, before you ask, I used the main gte nameserver (4.2.2.1) in order to use a neutral nameserver (ie not mine and not my ISP's). Check to see those test results with your domain name and IP addresses. -- Blue skies... Todd | Get a bigger hammer! | What does IIRC mean? | | http://www.mrball.net | --OpenLDAP Mailing List | | http://faq.mrball.net | | Attachment:
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