Beginning Aug. 3, 2010 all Form I-129F petitions being filed by a U.S. citizen on behalf of a fiancé(e)  or spouse must be submitted to the USCIS Dallas Lockbox facility.
For U.S. Postal Service:
USCIS
PO Box 660151
Dallas, TX 75266
For Express mail and courier deliveries:
USCIS
Attn: I-129F
2501 South State Highway 121 Business
Suite 400
Lewisville, TX 75067
Detailed guidance [...]