When trying to sell a domain name, I believe the most important thing is getting in touch with the right person at a particular company. If you call or email the wrong person at a company, you might not receive a reply when that company might be willing to spend the most money of any prospect for a domain name.
I’ve seen and used a few lead generation tools. It seems that most are able to provide a domain name seller with the Whois contact email address for potential prospects. Some tools are better at finding targeted prospects than others, although I would argue that doing this by hand is better than by using a tool.
That being said, the Whois email address is quite possibly not the best email address to use, and that is where searching for the right contact by hand is important. Many companies have a dedicated Whois email address, and the person or group who monitors this email address is responsible for maintaining and renewing the domain names. They may not be responsible for marketing decisions related to domain name acquisitions. For example, the IT department may not have the authority to buy a $25,000 domain name that will be used by the marketing department. If you solicit an IT person about this, they will likely ignore your email, especially if they are busy (hint: most are busy).
I use a variety of tips and tricks to find the right contact at a company. Most take a bit of time because many of the people I need to contact don’t have their email addresses listed in the obvious place. I do my best to learn about the company and the way it works because ensuring my email is read by the right person is the key. For instance, with some smaller or medium sized companies, the President or CEO might be the best person to contact, but with a larger company, the CEO would be too senior, and an executive assistant may simply delete the email.
In my opinion, when you are sending out emails, it is far better to send out 5 highly targeted emails than 100 untargeted emails.