I received an RFE that was sent out on 6/27 a few weeks ago for 2005 tax returns and w-2's. I sent back the reply by express mail on 7/8 and delivery confirmation by usps showed it was delivered on 7/10. But I have not received an email from uscis acknowleding receipt yet.I did my biometrics on 6/26 The LUD on my account was 6/27 saying the RFE was sent out and i received an email the next day. Should I try to contact them or should i give them a few weeks? For those who received RFEs, did you all get emails acknowleding receipt of the RFE by uscis? Thank you.