Several forms should now be sent to USCIS lockbox facilities rather than to USCIS Service Centers. These forms are:
• I-129F
• I-130
• I-140
• I-526
• I-539
• I-817
On the latest version of each of these forms, the new filing instructions can be found. These forms are available for free here.
The change occurred August 3, 2010. Applications already on their way to the service centers will be automatically rerouted to a designated lockbox. This will occur for a period of 45 days, after which packages will be returned to the applicant with a letter stating the new filing instructions.