I get emails about buying domains all the time. I always ignore them. If I get a second one from the same person, I always reply "the domain is not for sale at this time".
I think this is mostly because I don't have the energy to engage in email negotiations when I don't know whether to take the other person seriously. No one ever opens with an offer, perhaps if they did and it was interesting, I'd follow up. But since I'm not actively selling anything, they'd need to draw me into the process somehow.
No one ever calls. It feels wrong to say it, but in a case like this you can probably get a lot more mutual understanding in two minutes on the phone than 10 times that much time thinking about and writing email.
On the other hand, I really don't like unsolicited phone calls either, and there's no way in heck I'll ever return a voice mail inquiring about a domain...