Quote from: ArticMine on January 24, 2017, 03:06:50 AM

This kind of attack works because the spammer sends spam at a much faster rate than the Bitcoin network with its fixed 1 MB blocksize can possibly mine. There is consequently little or no cost to the spammer other than the spammer's own bandwidth. There is a significant cost to the network; however in driving up the bandwidth costs of those of us who run full nodes, with the likely result of driving down the number of full Bitcoin nodes.

A ~60% effective blocksize increase via say SegWit alone will not address this kind of spam attack.

Feerate filters will generally drop spam transactions and prevent those with too low of fees from getting relayed. The block size limit is actually fairly effective at preventing most of the spam from getting mined. What you're missing is that the resources costs to nodes for spam transactions that get mined are far higher than those that do not. Raising the block size actually has the effect of making spam attacks worse since more spam would be mined and take up resources/create more UTXO's.