Bosman: if a feature works only for 10% (provided 10% are internal and 90% external) of the mails either the feature must be removed or there must be a warning telling the user that such feature only works with internal users. So, technically speaking the 2 Receipts are different. Once you install the Boomerang add-on, compose your message, and click on 'Read Receipt' from the ribbon, or open the Boomerang menu and click 'Request read receipt & track clicks' from the taskpane. Receipts from internal recipients have one kind of icon, from external they appear as a mail. How to add a read receipt with Boomerang for Outlook. Daneke: even though your answer doesn't provide a solution, it is the best explanation on why this feature doesn't work with external servers. At least during these tests using well known destination mail servers. I regularly receive the both Receipts (delivery and read). your suggestions were focused on the fact that the destination mail server doesn't allow Receipts. The conclusion is: even in the best scenario (destination mail server allows Receipts to be sent back to the sending mail server) the Tracking Page only works with internal users. Dear Contributors, thank you for the support and for taking the time to reply.

Outlook read receipt tracking