Re: Configuring Exim for mail delivery

From	mo <mo777@gmx.net>
Newsgroups	linux.debian.user
Subject	Re: Configuring Exim for mail delivery
Date	2016-10-01 12:40 +0200
Message-ID	<snpS2-7al-23@gated-at.bofh.it> (permalink)
References	<sncBs-6LW-5@gated-at.bofh.it> <snhKO-1ya-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> I'll assume you have a home network and are trying to connect to send
> mails between machines on that network, and additionally be able to send
> email to domains outside your network.

That is right ;)

> I'm also assuming that you don't have specific domains for your own
> machines, so that when you send mail outside you want to use an email
> provider such as gmail, or hover, etc.

Also true ;)


> 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?

> 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? :)

> 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

> 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...

> If the target email domain is not present in hubbed_hosts, then a
> default "smarthost" configuration will fall through the hubbed hosts
> router and arrive at the smarthost router, which in my case then tries
> to use my mail provider to send a mail to a local machine, which is
> doomed to failure because the outside provider cannot see my individual
> machines on my local network.
>
> If you really should be using the "internet" configuration, you still
> need hubbed_hosts for local mails because whereas the hubbed_hosts
> option just leaves it to the local network to figure out what it is
> talking about, an internet-configured exim will attempt to find and send
> to the target machine. To do so, it will send out a DNS request to
> resolve the ip address of the target host. Avahi won't catch this, and
> unless you are running a DNS server locally on your network (most people
> don't, and many home network routers don't include one) that request
> will go out of your network to the DNS server provided by your ISP. That
> DNS server, being outside your network, won't be able to resolve your
> local machine names and so won't be able to give you back an IP address
> to use, unless your target machines are publicly individually visible on
> the Internet, which is unlikely if this is a home configuration we are
> talking about here.
>
> So the configuration you are after is local domains specified in
> hubbed_hosts, and everything else falls through to either a smarthost or
> a dns-based attempt to send outside your network.
>
> Hope that helps, let us know if you need more help.

Your explanation helped a lot ;)

> Mark
>


Greets

mo

Thread

Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-09-30 22:30 +0200
  Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 00:50 +0200
  Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 04:00 +0200
    Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 12:40 +0200
      Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 13:30 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 13:50 +0200
          Re: Configuring Exim for mail delivery Clive Menzies <clive@clivemenzies.co.uk> - 2016-10-01 14:00 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:10 +0200
      Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:30 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:40 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:00 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:00 +0200
        Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 15:00 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:10 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:40 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:20 +0200
            Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 16:40 +0200
      Re: Configuring Exim for mail delivery Teemu Likonen <tlikonen@iki.fi> - 2016-10-01 16:00 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:20 +0200
  Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 11:10 +0200
    Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 12:10 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 12:40 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
        Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 14:30 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:30 +0200
            Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:00 +0200
              Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:10 +0200
      Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:10 +0200
    Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 13:40 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
    Re: Configuring Exim for mail delivery rhkramer@gmail.com - 2016-10-01 14:20 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:30 +0200
    Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 18:30 +0200
      Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 20:20 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 22:50 +0200
          Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 00:30 +0200
            Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 02:30 +0200
              Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 13:10 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-02 10:50 +0200
        Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 23:10 +0200
          Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 00:40 +0200
            Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 02:10 +0200
              Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 14:00 +0200
                Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 14:50 +0200
                Re: Configuring Exim for mail delivery Gene Heskett <gheskett@shentel.net> - 2016-10-02 15:20 +0200
                Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 15:50 +0200
                Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 15:40 +0200
                Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 17:30 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 22:50 +0200

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