Quote from: nutildah on January 18, 2019, 03:30:11 PM

So, does a recipient necessarily need prior knowledge that they are about to receive some coins

Yes. Grin transactions always work in a multi-step process like this:

Quote from: theymos on January 15, 2019, 07:32:06 AM

1. The sender runs grin wallet send -m file -d FILE.txt GRIN_AMOUNT, which creates the file FILE.txt.
2. The sender gives FILE.txt to the recipient.
3. The recipient runs grin wallet receive -i FILE.txt, which creates another file FILE.txt.response.
4. The recipient gives FILE.txt.response to the sender.
5. The sender runs grin wallet finalize -i FILE.txt.response, and the transaction is done.

There are also methods involving IP addresses, keybase.io, and a "grinbox address" service, but behind-the-scenes these methods do the same steps as above, where the sender and recipient need to cooperate in order to form the final transaction