Hassio fails on SMTP Notification with attachments >100kb

I’ve been using Hassbian and am trying to migrate to Hass.io however my SMTP notifications are failing in Hass.io (but work fine in Hassbian).

I’ve done a bit of testing and it seems that when I’m using Hass.io and attach images to my notifications, once the sum of all attachments approaches ~100kb then i get the below error.

This does not happen with “Hassbian 0.59.2” and I can attach a large number of images without issues but occurs on every version of Hass.io I’ve tried including the latest “Hass.io 0.61.1”

Any help would be greatly appreciated. This is stopping me from moving to Hass.io

2018-01-20 23:07:29 ERROR (MainThread) [homeassistant.core] Error executing service <ServiceCall notify.email_notification: title=<homeassistant.helpers.template.Template object at 0x6d807630>, message=<homeassistant.helpers.template.Template object at 0x6d807330>, data=images=['/config/cbr.jpg', '/config/mbr.jpg', '/config/lr.jpg']>
Traceback (most recent call last):
  File "/usr/lib/python3.6/smtplib.py", line 354, in send
    self.sock.sendall(s)
  File "/usr/lib/python3.6/ssl.py", line 972, in sendall
    v = self.send(byte_view[count:])
  File "/usr/lib/python3.6/ssl.py", line 941, in send
    return self._sslobj.write(data)
  File "/usr/lib/python3.6/ssl.py", line 642, in write
    return self._sslobj.write(data)
socket.timeout: The write operation timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/homeassistant/components/notify/smtp.py", line 178, in _send_email
    mail.sendmail(self._sender, self.recipients, msg.as_string())
  File "/usr/lib/python3.6/smtplib.py", line 882, in sendmail
    (code, resp) = self.data(msg)
  File "/usr/lib/python3.6/smtplib.py", line 568, in data
    self.send(q)
  File "/usr/lib/python3.6/smtplib.py", line 357, in send
    raise SMTPServerDisconnected('Server not connected')
smtplib.SMTPServerDisconnected: Server not connected

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/homeassistant/core.py", line 1010, in _event_to_service_call
    yield from service_handler.func(service_call)
  File "/usr/lib/python3.6/site-packages/homeassistant/components/notify/__init__.py", line 137, in async_notify_message
    yield from notify_service.async_send_message(**kwargs)
  File "/usr/lib/python3.6/asyncio/futures.py", line 332, in __iter__
    yield self  # This tells Task to wait for completion.
  File "/usr/lib/python3.6/asyncio/tasks.py", line 250, in _wakeup
    future.result()
  File "/usr/lib/python3.6/asyncio/futures.py", line 245, in result
    raise self._exception
  File "/usr/lib/python3.6/concurrent/futures/thread.py", line 56, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/lib/python3.6/site-packages/homeassistant/components/notify/smtp.py", line 171, in send_message
    return self._send_email(msg)
  File "/usr/lib/python3.6/site-packages/homeassistant/components/notify/smtp.py", line 183, in _send_email
    mail.quit()
  File "/usr/lib/python3.6/smtplib.py", line 983, in quit
    res = self.docmd("quit")
  File "/usr/lib/python3.6/smtplib.py", line 420, in docmd
    self.putcmd(cmd, args)
  File "/usr/lib/python3.6/smtplib.py", line 367, in putcmd
    self.send(str)
  File "/usr/lib/python3.6/smtplib.py", line 359, in send
    raise SMTPServerDisconnected('please run connect() first')
smtplib.SMTPServerDisconnected: please run connect() first

The script that is being executed is as below:

  email_script:
    sequence:
      - alias: Send Email
        service: notify.Email_Notification
        data:
          title: 'HASS Configuration File TEST5'
          message: 'Sent by Home Assistant, {{now().strftime("%A %H:%M:%S %d-%m-%Y")}}'
          data:
            images:
              - /config/cbr.jpg
              - /config/mbr.jpg
              - /config/lr.jpg

Does anyone know what I can do to resolve this issue in hassio?