Which address to ship N-400 to? Thanks!

[w124]

Hi and what a blessing this forum is for those applying and with questions!

First, THANK YOU to the forum and for your interest in helping my wife and I. I am assisting her in the filing process

I would like to ship the N-400 via USPS First Class Mail WITH:

1)Certified Mail Receipt (Delivery Confirmation and Tracking)
and
2) Return Receipt (the 'postcard' like form that the receiver signs on delivery and ships the card back to me)

I was wondering if I should use the Lockbox (P.O Box) or Express/Courier deliveries (an actual 'live' address)?

I don't ship paperwork often so I'm guessing I should use the Lockbox address, since it's NOT express/courier (such as USPS Priority or Express Mail), BUT I need a signature from the receiver...

Thanks for your guidance and assistance!

 

[DreamUSA]

use FEDEX or UPS....my 2 cents.. for street address not PO.