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  1. #1
    Join Date
    Apr 2005
    Posts
    30

    mx record point to 127.0.0.1

    this is an mx record of public.com:

    ========================
    ;; QUESTION SECTION:
    ;public.com. IN MX

    ;; ANSWER SECTION:
    public.com. 86400 IN MX 100 mx1.public.com.

    ;; AUTHORITY SECTION:
    public.com. 259200 IN NS ns1.25.com.
    public.com. 259200 IN NS ns2.25.com.

    ;; ADDITIONAL SECTION:
    mx1.public.com. 86400 IN A 127.0.0.1
    ns1.25.com. 259200 IN A 204.228.229.166
    ns2.25.com. 259200 IN A 204.228.229.167

    ====================

    And this is my postfix log:

    ======================
    Local Bounce:
    To [email protected] Msg="mail for public.com loops back to myself" : 1 Time(s)

    =========================

    Any one know the way to prevent this problem ?

    Thanks alot

  2. #2
    Join Date
    May 2001
    Location
    Montreal, Quebec
    Posts
    589
    Change 127.0.0.1 to your mail server IP. 127.0.0.1 is the loopback.

  3. #3
    Join Date
    Apr 2005
    Posts
    30
    Thank for reply Illogix, but maybe my post confuses you.

    public.com is not my domain. It belongs to spammer I believe. I believe it want to email to none-exist email accounts to my mail server. My mail server try to reply the error back to @public.com, but public.com has mx record 127.0.0.1. 127.0.0.1 is a loop back interface, that why my server complain "To [email protected] Msg="mail for public.com loops back to myself" .

    I have a temporary solution now, which is any mails from public.com just send to a /dev/null . However I want a solution for any emails from any domain, which has mx record set to 127.0.0.1 (loop back interface), the server will ignore.

    This trick is very clever, because almost all mail servers accept messages from it own localhost. For example, syslog send message out using [email protected]

    My mail server running postfix
    Last edited by dnguyen; 04-17-2005 at 01:07 PM.

  4. #4
    Join Date
    Apr 2005
    Posts
    30
    For example,

    Your email domain is illogix.com, set mx recored to 127.0.0.1. You try to email to [email protected] from address [email protected]. Yahoo.com try to reply the error non-exist account back to [email protected], but illogix.com has an mx record point to 127.0.0.1. It mean yahoo.com try to send a reply back to itself.

    I hope you got my point.

    How do hosting people here prevent this trick ?
    Last edited by dnguyen; 04-17-2005 at 01:23 PM.

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