I just wanted to let everyone know that after much considered review, new lower policy limits on the number and size of related unconfirmed transactions that will be accepted in to the mempool and relayed have been merged into the master branch of Bitcoin Core for 0.12 release. The actual limits were merged in PR 6771 and discussion of these limits can be found in this previous email to the dev list and discussion of the new lower limits here . The new limits are: 25 unconfirmed ancestors 25 unconfirmed descendants 101kb total size with unconfirmed ancestors 101kb total size with unconfirmed descendants. These limits are just policy and do not affect consensus. They can be modified by command line arguments. Thanks, Alex