Yardbook recently added the feature for approval of estimates. I sent and estimate to a customer and they clicked the approved button it then sends me an email stating that the estimate #1111 has been approved with the estimate attached. I find this to be really neat and have more of a paper trail that work was approved vs she said too. I started using yardbook and have been very pleased with the features that are free. Make running a small solo operation very efficient and professional for free.