Once you’ve snoozed an email, it will disappear from the inbox. At the specified time, it will reappear, and you’ll get a notification for it, as if it were a newly-arriving message.
You can unsnoozed an email that you’ve snoozed but still were able to deal with.
Select an email in the Snoozed category.
Click the Snooze button on the toolbar.
The Snooze menu appears again, and in addition to unsnoozing, you could reschedule the email to instead reappear at another date or time, using the same options as before.
Select Unsnooze.
The email is unsnoozed and reappears in the Inbox.