I have had nearly no luck emailing end users. I have emailed people who have a hypenated .net with the non-hyphenated .com and either heard nothing or 'don't SPAM me' even if I am asking just $XX. People either get domains or they don't and, frankly, even today, most don't.
Make sure that you are listed at Sedo and possibly other retail/wholesale-retail places as you are at least selling to people who are looking. Cold calling a domain has about as much success as you likely would have going door to door to sell your house even if you were offering it at a good price.
Don't forget that selling a name for an OK price is better than never selling it for a great price.