Delivery Receipt function doesn't work anymore?

Hi Mr. Kumara,

We're sorry for the delay in response to your issue reported above. 

The files that you have recently shared are listed in Home > Recent. When the recipient views the file, you get a notification in Acrobat and an email. It also depends on how the file was shared. Did you share the file using an 

anonymous public link, an Email attachment, or a personalized invitation for viewing or commenting?

To view and track all the files shared for viewing, do the following steps mentioned under Track Shared files in this help article:

https://helpx.adobe.com/in/acrobat/using/sharing-pdfs.html 

• If you were receiving the notification earlier and all of the sudden it stopped. Then please check if anything has changed this, like a recent update? 
• Open Acrobat/Reader>help>About Acrobat Reader or check for update\
• Also, try with a different file and share that for commenting. 

Thanks,

Akanchha