If you have enabled Delivery Notifications for Swiss Post, you have the option of supplying some Free Text to be included in your notification messages.
More information on Swiss Post's notification messages, message templates and inclusion of Free Text is available on their website, here: www.post.ch/en/business/a-z-of-subjects/practical-tips-recipient-customers/recipient-services-parcels/notification-services?shortcut=www-post-ch-post-e-log-avisierungsservices-details
Note: If you've selected SMS notifications, anything entered into the 'Notification Free Text 2' field will be ignored.