Re: [Exim] Bogus MX records

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Author: Harald Meland
Date:  
To: grep
CC: exim-users
Subject: Re: [Exim] Bogus MX records
[George Bonser]

> There are quite a few domains out there that have their MX record set to
> a name that resolves to 127.0.0.1
>
> The problem is that it causes mail to be relayed for those domains when
> relay_domains_include_local_mx = true
>
> Is there some way to tell exim not to consider 127.0.0.1 as a valid MX?


Yup, router option 'ignore_target_hosts'. We're currently using this:

  # Don't allow domains whose single MX (or A) record is a
  # "special-use IPv4 address", as listed in RFC 3330.
  ignore_target_hosts = \
    # Hosts on "this network"; RFC 1700 (page 4) states that these
    # are only allowed as source addresses
    0.0.0.0/8 : \
    # Private networks, RFC 1918
    10.0.0.0/8 : 172.16.0.0/12 : 192.168.0.0/16 : \
    # Internet host loopback address, RFC 1700 (page 5)
    127.0.0.0/8 : \
    # "Link local" block
    169.254.0.0/16 : \
    # "TEST-NET" - should not appear on the public Internet
    192.0.2.0/24 : \
    # 6to4 relay anycast addresses, RFC 3068
    192.88.99.0/24 : \
    # Network interconnect device benchmark testing, RFC 2544
    198.18.0.0/15 : \
    # Multicast addresses, RFC 3171
    224.0.0.0/4 : \
    # Reserved for future use, RFC 1700 (page 4)
    240.0.0.0/4


on the appropriate router. Note that our servers are not IPv6
enabled, so we don't have to deal with the similar IPv6 ranges.
--
Harald