Re: [exim] exim4, gmail and 550-5.7.1

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Author: Chris Knadle
Date:  
To: exim-users
Subject: Re: [exim] exim4, gmail and 550-5.7.1
Robert Steinmetz:
> Based on the link I listed in my first post I have come up with a potential
> solution:
>
> Can anyone comment on whether it should work or not?


It might not work -- the issue I see is in the router:

[...]
> ipv4_only:
> driver = dnslookup
> domains = +ipv4_force_domains
> transport = ipv4_smtp
> ignore_target_hosts = <; 0::0/0|


The documentation explains that the "ignore_target_hosts" option discards
matching IP addresses, and for the dnslookup driver if all of the IP
addresses are discarded then the router declines. The mail would then go
onto another router/transport.

i.e. the issue has to do with the DNS lookup. If the DNS lookup returns
purely IPv6 addresses, then this router will end up being skipped.

This is why Ian was suggesting either:

   disable_ipv6 = true
     or
   dns_ipv4_lookup = *


Note that the dns_ipv4_lookup= option takes a domainlist, so you could do
something like:

dns_ipv4_lookup = ipv4_force_domains

where ipv4_force_domains was from your example:

[...]
> domainlist ipv4_force_domains = \
> gmail.com : \
> googlemail.com : \
> virgin.net : \
> linkedin.com : \
> virginmedia.com


[...]
> Finally adding a file in /etc/exim4/conf.d/transports
>
> 50_exim4_config_ipv4_only_transport:
>
> I'm a little puzzled by the one in the example.
>
> ipv4_smtp:
> driver = smtp
> dkim domain = mydomain.co.uk
> dkim_selector = x
> dkim_private_key = /usr/exim/dkim.private.key
> dkim_canon = relaxed
> interface = <my.v4.ip.address>|
>
> Why can't I simply use the existing smtp remote_smtp transport with
> the some relatively simple edits? This example contains a directive
> that limits it to using ipv4 by specifying the interface using an
> ipv4 address.


Unfortunately it seems that's not what the 'ignore_target_hosts' and
'interface' option combination will do, at least not by themselves.

> Seems like somewhere should be a directive like
> disable_ipv6 = true or dns_ipv4_lookup = *


This is what Ian Eiloart had mentioned.

> I also wonder if these dkim statements conflict with the rest of the
> basic debian configuration.


Are these dkim options in the example? If so, they're not a requirement
unless this is also what you have in the remote_smtp transport.

If you haven't already, I would suggest reading Chapter 3 of the Exim
documentation, "How Exim receives and delivers mail". AFAIK each individual
mail should pass through a single router and transport, and this choice is
made by whatever router matches.

-- Chris

--
Chris Knadle
Chris.Knadle@???