請問這個關於485的EMAIL是什麽意思？什麽情況下會收到這樣的EMAIL？

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The last processing action taken on your case
Application Type: I485 , APPLICATION TO REGISTER PERMANENT RESIDENCE OR TO ADJUST STATUS

Current Status: Document mailed to applicant.

On January 7, 2008 we mailed the document to the address we have on file. You should receive the new document within 30 days. If you do not, or if you move before you get it, call customer service. If you have questions or concerns about your application or the case status results listed above, or if you have not received a decision from USCIS within the current processing time listed*, please contact USCIS Customer Service at [phone].

*Current processing times can be found on the USCIS website at www.uscis.gov under Case Status and Processing Dates.*** Please do not respond to this e-mail message.