How are Delivery and Read receipts or Out of Office Autoreply messages analyzed?

• Delivery receipts are generated by the Exchange server. They have a special event number in message tracking files. Importing these events is optional.
• Read/Not Read receipts are generated by the email client, so they will appear as a standard message in message tracking files. Promodag Reports imports and counts them as standard messages.
• Out of Office Autoreply messages are imported and counted as any other standard messages.

It is possible to exclude these messages from mailbox traffic reports from version 11 onwards, see this blog post: Version 11 comes with Office 365 content search and email activity reports and Enhancement of the Tag Messages by Subject option.