PP Receipts vs RP Receipts (E-mail Receipts/Confirmations)

After the random selection is done in its entirety -

I keep hearing a lot that PP receipts are issued first and then RP receipts.

Is this for physical paper receipts or even for e-mail receipts? I am guessing e-mail receipts time frame should be the same for all applicants who were picked in the random selection process.

For non-PP candidates, receipts are sent as hard-copies. I don’t think they are notified over email.

Yes, you are right. I contacted USCIS customer rep about this. They mentioned the same.
PP - Receipt by both e-mail and mail.
RP - Receipt just by mail.
(No word of random selection date yet)