Author: Chris Knadle Date: To: Ian Eiloart CC: exim-users@exim.org Subject: Re: [exim] exim4, gmail and 550-5.7.1
Ian Eiloart: >
>> On 15 Dec 2015, at 02:35, Chris Knadle <Chris.Knadle@???>
>> wrote:
>>
>>
>> I'm wondering if "interface = <IPv4_address>" could be used within the
>> remote_smtp transport to force using a local IPv4 address outbound.
>
> The docs suggest otherwise. The value is a list addresses, and the whole
> thing is ignored "if none of them are the correct type". I presume the
> correct type is one that’s been selected from MX records, or an option in
> a router or transport.
Yes, reading the section it seems to be based on the $host_address, which is
presumably filled via a DNS lookup on $host, which is the host of which an
outbound SMTP connection is about to be made. So to force IPv4 one would
need to control the DNS lookup to insure an IPv4 address was returned.
> So, if Exim has already decided to use IPv6, then
> then this option will be ignored and "the system’s IP functions choose
> which interface to use if the host has more than one".
>
> I think the easiest thing to do is to say
>
> disable_ipv6 = true
> or
> dns_ipv4_lookup = *
