About email messages
Email messages are the email templates used to send out scheduled report packs. If you don't create an email template to use with your report packs, the default system one is used.
To delete an email message, you must have the correct permissions. You can only delete an email message if it's not being used in a report pack. If you select multiple email messages to delete and one of them is used in a report pack, none of the selected email messages are deleted.