Problem with thousands of emails

I have a Pi2 running Cayenne, the dashboard appears to work fine however I am getting thousands of emails from the gmail account I have set up on the Pi - failure notifications on emails sent to root.

Not sure I know where to start?

Can you paste / post a screen shot the email that you are receiving?

-B

Mail Delivery Subsystem mailer-daemon@googlemail.com
9:46 PM (12 minutes ago)

to me
Delivery to the following recipient failed permanently:

 postmaster@pi2

Technical details of permanent failure:
DNS Error: 207430145 DNS type ‘mx’ lookup of pi2 responded with code NXDOMAIN
Domain name not found: pi2

----- Original message -----

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=gmail.com; s=20120113;
h=message-id:from:date:to:subject:mime-version
:content-transfer-encoding;
bh=HLCo9VcELhp5PYwX3vbFRCny5s3VA2fOoM957+WpRs0=;
b=RuMdFEfHJ7HuHmmJ0W47SE6VILWIknKmrm18GXrXfbpD4eeVrUReFTc3deZKjQO4Vw
9bn+F90HAxuxNlzrGZy6hm7AgmUiznWEqV687+DFoe9o9WboooRj/+TqYjoInNzLo5M3
lolsOw+CHkSPdO3gMhj/5cT70qt2J3YkNJ6hHHjdfNJngFk/AJGl2DapuMsgGLu2hH9R
sJAQXTo8TO0VzwtbzGq21X7GA20DniUweMJ/jqJxRYJYTpS+YtHnObVZr6lbG+DdpynX
sTeTET23357TcmobX1mhvHQk6yCiPlL8oZN4155AzMStOrAzrenZqB6DpO59gqqM9gtF
lryA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20130820;
h=x-gm-message-state:message-id:from:date:to:subject:mime-version
:content-transfer-encoding;
bh=HLCo9VcELhp5PYwX3vbFRCny5s3VA2fOoM957+WpRs0=;
b=TDZ0eL9+gtgtuZROPo5toEse9BwlLizk5j2xCFP6kp7KHMA9ITZYYy4uac1tErxzh8
G5xRkF0Obuxwm71hat0K1hQNNLEJJG2DDoU9R07N4SWlqTVpyJS5bLbeuhV8t/fgheZI
a51pBkHz0XdytexCnESZrXv889sPW+nZaR+3Uj3jFkGlGgLYQX7I/iylTpoa9Qiq1iyU
f3RibU9icrNNHxnNyHi9JtlC4c4E4m+rzyTrJZxmQPOMPehgckMPxN86hvXBnwpZe31P
RaknyKXpNKEq6Xp0Q4qiC0yt0LZ7oZXMHSBV5NaaNs2I0BwZdhKVPWJUKTDPl0iIRp7F
XjIg==
X-Gm-Message-State: AA6/9RmIcUClAvcpIH93spZEBz7k9HtS7w/aHsVUXIgTIMiXYR778D9BddZcHmGT3ARYmA==
X-Received: by 10.107.3.78 with SMTP id 75mr24013810iod.75.1476755164290;
Mon, 17 Oct 2016 18:46:04 -0700 (PDT)
Return-Path: MYADDRESS@gmail.com
Received: from pi2 (CPEac220b859940-CM00fc8d09c720.my.isp. [MY ISP IP])
by smtp.gmail.com with ESMTPSA id j98sm14620789ioo.11.2016.10.17.18.46.02
for postmaster@pi2
(version=TLS1 cipher=AES128-SHA bits=128/128);
Mon, 17 Oct 2016 18:46:03 -0700 (PDT)
Message-ID: 58057edb.652f6b0a.4ba6d.5e2a@mx.google.com
From: root MYADDRESS@gmail.com
X-Google-Original-From: root (Cron Daemon)
Received: by pi2 (sSMTP sendmail emulation); Mon, 17 Oct 2016 21:46:02 -0400
Date: Mon, 17 Oct 2016 21:46:02 -0400
To: root
Subject: Cron root@pi2 /etc/myDevices/crontab.sh
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/root>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=root>