You can also receive push notifications via Pushover.
To get started sign up for an account on their website: https://pushover.net
Once you’ve got your Pushover account, get your User Key, located right on the next page once you log into your Pushover account. (same link as above)
Just copy/paste your User Key into any of your contact lists:
If you have any other questions about Pushover be sure to read their FAQ: https://pushover.net/faq or contact their support.