In a form in production, tap on the button with the checkbox icon in the top left corner of your screen to activate the form validation:

A green thumbs up icon will appear in the button and indicates that your form is compliant and all the invalidities have been addressed.

A red thumbs down icon will appear in the button and indicates that your form is non-compliant and contains invalid field.

Invalidities disappear when a mandatory field is filled or when limit has been reached in a specific field. For the last possibility, an action must be taken and linking a form to the field will remove the invalidity on it.

You may validate a form when you are archiving a form.

Notifications can be used to alert a colleague through an email.
This action will not remove the invalidity, but will allow to send a message to an employee in your company to let him/her know about the current situation.
​Notifications don't require any SMTP settings configuration or anything else on your end.
​The employees with no valid email addresses as usernames can still use the notification feature, as long as the receiver has a valid email address as a username.