[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