What I don't get is: Why do wallets give you the ability to spend 1 satoshi as a fee or even 0 as a fee? If the transaction is going to get stuck, why not stablish a minimum fee that guarantes this not to happen? coz noobs will always tend to look for free shit, and will always pay no fees and think everything is fine, then shit like OP happens...
Fee-less shipping. Nobody want to impose fee. Almost all wallets' default fee is 0.0001/1000 bytes. Don't change it and don't change the mod, like shorena told.
P.S. I think there is a minimum fee but it isn't must:
52. /** Fees smaller than this (in satoshi) are considered zero fee (for relaying and mining) */
53. CFeeRate minRelayTxFee = CFeeRate(1000);
Thanks, shorena!