[ALUG] I need an E-Mail expert to help me solve this

Chris Green cl at isbd.net
Sun Feb 19 11:37:16 GMT 2017


I have an E-Mail requirement/problem that I've wasted several hours on
over the past few days to little effect.  Maybe someone here can help.

My home (linux) machine runs all the time and hosts the domain zbmc.eu
which is registered at gandi.net.  The zone file there is configured
to point at my home machine and the MX record is set up too:-
    chris at cheddar$ host zbmc.eu
    zbmc.eu has address 84.92.49.234
    zbmc.eu mail is handled by 10 zbmc.eu.
    chris at cheddar$ 
84.92.49.234 is my PlusNet ADSL connection.

I have several domains hosted at TsoHost with associated E-Mail
addresses (e.g. chris at isbd.co.uk, chris at isbd.net, cl at isbd.net). These
all eventually forward their E-Mail from the TsoHost servers to
chris at zbmc.eu.  I run a postfix server on my home machine which
receives these E-Mails and puts them in my mail spool.  This has been
working fine for several years.

However I now want to send E-Mail from the 'outside world' to
chris at zbmc.eu.  The specific requirement is to send errors from cron
on various SBCs to me and I originally thought it was a
misconfiguration at the sending end was the problem but it's more
general.

No mail sent from outside to chris at zbmc.eu arrives on my home machine,
it just disappears, no errors, no bounces, nothing.

Bit it works from the TsoHost cloud servers, why can they send E-Mail
successfully to chris at zbmc.eu whereas no one else can?

I have done lots of tests and experiments so far:-

    I've tried sending from three different sites (PlusNet, Gandi and
    a Linux box) to chris at zbmc.eu, mail just disappears.  Identical
    E-Mail sent to chris at isbd.net arrives OK.

    I have a postfix server set up on my Beaglebone black in France
    (to send the cron messages).  If I monitor the mail.log file when
    connecting to the SMTP server at TsoHost (mail3.gridhost.co.uk)
    the logging is exactly the same for mails sent to chris at zbmc.eu as
    for mails sent to chris at isbd.net.

    Wierdly (and this is what confused me somewhat at the start) I
    have an identical postfix setup on a Raspberry Pi on my home LAN,
    also for sending cron errors.  It connects directly to the same
    SMTP server at TsoHost as the Beaglebone does.  However E-Mail to
    chris at zbmc.eu from the Pi works!

So it would seem that there's something 'out there' that's routing
mail for zbmc.eu to the wrong place (or nowhere), but it doesn't get
at the mail sent from within TsoHost for some reason. I.e. TsoHost
seems to do what I hoped/expected with E-Mail for chris at zbmc.eu but no
one else does.

Help!  :-)

-- 
Chris Green



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