Bitcoin: Insert again the option of doing transaction less than 1 sat/byte

I think all you need to do is change these settings from the defaults:

-mintxfee=<amt>
     Fees (in BTC/kB) smaller than this are considered zero fee for
     transaction creation (default: 0.00001)

-minrelaytxfee=<amt>
     Fees (in BTC/kB) smaller than this are considered zero fee for relaying,
     mining and transaction creation (default: 0.00001)

@dooglus,

It won't work that easily. The whole network does not usually relay transactions below 1 sat/byte and even if you can find some nodes to relay, the miners won't pick up the transaction. I did a test, set up a 0.000001 relay fee (10x lower than the default) and my node picked up a few such transactions. Some even show up on block explorers https://btc.com/895d90280089701e00230089337dc8304fbf339d4f1eb8d4f63b606a5abe1b1c but miners do not include them in blocks.

miners do not include them in blocks

That sounds like something to talk to the miners about rather than being an issue here.