Urgent help! EAD RFE mailing address to California Service Cente

We mailed RFE for EAD application using original envelop included using USPS certified mail. The mail must get lost somewhere b/c it has been over a week and USCIS hasn't receive it yet!

We are trying to send the requested information again, with a cover letter to explain things. But we do not have the orginal envelop anymore, and do not remember the exact mailing address on it. Could anyone who has received a RFE for EAD from California Service Center let kindly tell me the return mailing address on the envelop? Will there be a problem for not using the original envelop? What else can we do in this case?

Thank you so much for your help!