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View Full Version : Fake MX Records to reduce spam


arnb
11-25-2007, 07:39 AM
Has anyone been successful getting this technique to work on BH?

Using the MX record function on the control panel the MX records are added and modified, but I get no email. I notice the fake addresses have a IP of 0.0.0.0 and I suspect that is the issue. Additionally, when MX 0 is valid and MX (N>0) is invalid I get no mail.

MX setup 1
foo.org 0 fake.foo.org
foo.org 1 foo.org
foo.org 2 fake.foo.org
foo.org 3 fake.foo.org
foo.org 4 fake.foo.org

MX setup 2
foo.org 0 foo.org
foo.org 2 fake.foo.org

Background Information
Link:http://en.wikipedia.org/wiki/Anti-spam_techniques_%28e-mail%29#Fake_MX_Records
Fake MX Records

Virus infected spam bots ignore requirements that the email start at the lowest numbered MX record and move up the list if a failure occurs. They try the highest numbered MX records first thinking that the backup servers have less spam filtering than the low numbered MX servers. Spam bots usually do not retry on failure but move on to the next email address in their list. Thus adding fake high numbered MX records is an effective way to reduce incoming spam.

Some companies offer a service to point to their servers as fake MX records. However, this is considered dangerous because it gives them the ability to actually receive all mails by activating an SMTP server on the fake MX. Additionally there are privacy concerns because they usually gather statistics about all the rejected emails.

One can also reduce spam by having a fake lowest MX record as well. This causes real email to have to retry as well but it only adds a second to the delivery time. Some people report as much as 90% reduction in spam bot spam using this method.

mx1.example.com - 10 - dead IP
mx2.example.com - 20 - real server
mx3.example.com - 30 - dead IP

pppadmin
12-31-2007, 05:04 PM
You'll need to point the lowest fake MX record to a closed port otherwise a temporary error will be sent and will never move to the next MX record.

arnb
01-01-2008, 08:01 AM
Please post the format of an MX record with a port number and should you know a good blocked port number to use with Bluehost.