While not as flexible as a notification, you can hard code an email via script that can be called by a UI action. Below is an example:

var emailNotification = new GlideRecord('sys_email');

emailNotification.type = 'send-ready';

emailNotification.subject = 'Email subject';

emailNotification.body = 'Email body';

emailNotification.recipients = email-adress1 + ',' + email-address2;

emailNotification.insert();