Can I send custom notifications to my users from storehippo admin panel?

Yes, you can send custom notifications to your users via StoreHippo.

You will first need to add custom notification templates in Setting > Notification section of StoreHippo admin panel. Know how to add notification template: https://help.storehippo.com/topic/adding-notifications

You can then, send the notifications to the users from Customers > User section of the admin panel. For more details about how to send email notification, please refer:
https://help.storehippo.com/topic/send-notification-to-user