When I have been doing outbound outreach to sell domain names, I have been including a link to a Dan.com BIN landing page. My focus has been on less expensive domain names since they tend to sell more easily. With Dan landers, the buyer has two purchase options, including the ability to buy the domain name immediately or select a payment plan. It removes friction and facilitates a speedier sale.
When sending emails to a targeted group of prospective buyers, there are usually at least a few prospective buyers who would want to own the domain name. In my outbound email, I emphasize that the offer is time sensitive and available on a first come first serve basis. Not only does this serve the purpose of creating urgency, but it lets each buyer know this one of a kind asset is only available to the first person to agree to the deal. Once someone else buys it, they no longer can.