Hmmm... this is indeed peculiar.

However, there can be reasons it won't let you send without fee. For example, i believe the algorithm (in my fork and in official client) doesn't allow sending very small amounts, or amounts that does not have enough confirmations.

I have not removed all safeguards against sending money without fee, just some of them.

If you want to make sure it works as it should, you can build 0.3.21 version of the mainline client and compare the functioning of that with NFTF. If it is the same, then it works.

Unfortunately, i dont't have time to test it now, because I am going on holidays. When I am back (about 8 april), I am going to test it thoroughly.

Glad i could help.

It just ignores the fee if there is high probability that it won't be necessary.

It is quite safe for everyday usage, if you keep certain rules (eg. not resending money which don't have enough confirmations yet). Sending money which have at least 7 confirmations should be 100% safe, always.

Please do not tell people that it is 100% safe. This is not true and the whole concept of thinking users can tell which money they're resending is wrongheaded, the client has free run to pick from whatever inputs it wants in the wallet. I have helped users unstick their wallets several times as a result of this patch.

I've cautioned you about this in the past— and you responded by pointing out that you were direct about the risks and consequences. Now you violate that by claiming that it's 100% safe.

Yes, it's usually not problematic— after all the overwhelming supermajority of transactions do not need to pay a fee in any case. So yes, in any case where a fee wouldn't have been applied this is safe— but also pointless.  In cases where waiting a few hours would have made it no longer need a fee then this is safe enough (at worst you'll need to leave your client running for a few hours before your transaction goes)... but in cases where weeks would be required your funds will end up unusable for a long span of time unless someone helps you effectively hex edit your wallet.

I just get spammed with errors. Am I missing something?
http://pastebin.com/dpnDMAAj

Yes it does

Will do, thanks

What if there were different tiers of difficulty - if you only include transactions without fees, your difficulty is 'x', if you include transaction fees, it's 'y'. Dedicate one of the 2016 blocks to transactions without fees, so that if someone F's up, they definitely get processed within two weeks. There would be some shifting weirdness until the difficulty of the 50+fees vs. 50+0 evened out between the two different tactics, but it should eventually police itself such that it's reasonably equally profitable.

Haven't tried that yet, you are welcome to be the first