Re: Configuring Exim for mail delivery
On Sat 01 Oct 2016 at 12:36:10 +0200, mo wrote:
> >I just figured out how to get this working myself a week or two back, so
> >it's fresh in my mind. The key trick is the use of "hubbed hosts".
>
> Did you follow a specific book or guide?
The manual for exim4-config_files is the first place to look.
> >Exim configuration has the concept of "routers" and "transports".
> >Routers basically decide what to do with a message, and transports do
> >it. One of the routers configured by default in the Debian exim
> >configuration is for "hubbed hosts". What this means, is machines
> >capable of sending and receiving email ("hosts" in exim speak) that are
> >on the same LAN as this machine (connected by a "hub"). Note that this
> >"hub" could be your local home network router, and for these purposes
> >machines on WiFi and machines on a wired LAN would be considered on the
> >same hub, even though that isn't strictly true. The point is that
> >network packets can be addressed directly between the machines, they
> >don't require a router in between.
> >
>
> As far as i do understand this is that only machines which are defined as
> hubbed hosts can be send mail in the local LAN? Or am i misunderstanding
> something here? :)
hubbed_hosts can send mail wherever you want. For example:
example.com: smtp.example.com
would send mail to someone at example.com through smtp.example.com
(which could be a smarthost).
> >In Debian, this is achieved with Avahi. This is what allows you, if you
> >have MachineA and MachineB on your network, to do for example "ping
> >MachineA.local" from MachineB and expect MachineA.local to be resolved
> >into an IP address.
> >
>
> I'm not a friend of avahi to be honest, i much rather ignore it :D
Let's hope your IP addresses do not change.
> >In /etc/exim4, create a file owned by root called hubbed_hosts. In the
> >file, each line maps a "domain" (the part after the @ sign in an email
> >address) to a "host" (the name of a machine on your network, as it can
> >be reached from this machine). Put the domain first, then a tab
> >character (spaces may also be OK) and then the host. So for example I
> >have a machine on my network called affinity, and so in the hubbed_hosts
> >file on the machine I am sitting in front of now, I have two lines, one
> >saying "affinity.local<TAB>affinity.local", and the other saying
> >"affinity<TAB>affinity.local" (no quotes in the file). This tells the
> >local exim installation that any email address with @affinity.local as
> >the domain should be forwarded on to a machine called affinity.local,
> >and any mail with @affinity as the domain should be forwarded on to a
> >machine called affinity.local. Exim4 will then say "Connect to
> >affinity.local!" with no attempt to translate that into an IP address,
> >and Avahi daemon will answer "that is IP address WW.XX.YY.ZZ!" to which
> >exim will say "very well, connect to WW.XX.YY.ZZ!" and the exim4 on
> >affinity will wake up and co-operate to deliver the mail.
>
> I just did that and now mailing works flawlessly :D
> Just one questions: Why do i need hubbed_host entries? Should it not be fine
> alone to make a entry in /etc/hosts for the machines i want to send mail to
> (I do not operate a dedicated DNS server).
> This is something i dont really understand...
I'd suggest you try it and look at the logs.
--
Brian.
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