Brokering domain names can be a tough gig. Even when a prospective buyer is interested in a particular domain name, getting a deal closed can be challenging. A domain broker may send dozens of follow-up emails in order to get a buyer to agree to a deal or to induce a reasonable counter offer. It may even take a while to get a response from someone.
It is always neat to see how domain brokers handle follow-up emails with prospects. I think Uniregistry has a pretty neat system in place to enable its clients and brokers communicate with prospective buyers. From what I have seen working with various Uniregistry brokers on purchases, they seem to have their own creative ways to get a response.