I have received my permanent resident card and approval notice like 3 weeks ago but today I received an email from the USCIS saying that "the document we made based on the approval or registration of this case was mailed directly to the person to whom issued". 
What could this mean? What else would the USCIS send after sending the card?
Your help will be appreciated so much!
What could this mean? What else would the USCIS send after sending the card?
Your help will be appreciated so much!