If you or your users do not receive email notifications send from your website, the most likely scenario is that the webserver that runs your site is not authorised to sent emails on your behalf for example from an email like info@<your-domain>.co.nz
Google publishes instructions on how to Authorise email senders with SPF under https://support.google.com/a/answer/33786?hl=en
__What is a email notification?
Email notification can include (amongst others)
- user account notifications when a new account is set up
- emails in response to "requests a new password"
- webform submission notifications
- workflow moderation notifications
__Why does the webserver send emails on your behalf?
All email notification require a from email address, and to ensure the receiver of these emails that they come from a credible source the from emails are set to one of your emails.
See also other issues around email (future link)