How to request confirmation on reception?

This function you can set when writting a message. You have to check "Request a read receipt" from the drop down menu "More" placed in the same row with the button "Send message":

 

After recipient opens Your letter, a small window appears, asking recipient whether he wants to notify you about receiving it.

 

If recipient will choose yes, You'll automatically receive e-mail notification about it, including such information:

 


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