I would not email potential users as 99.9% of the time you will get no reply or a negative reply and the 0.1% will slam you with a CDRP, which is already heavily slanted towards their corporate overlords, but with a sales contact to hold up to the panelists, it's virtually a slam dunk win for the company.
Domains are not something that companies buy on the spur of the moment (that is unless you're liquidating for $100 or so) and all you'll get in return is trouble.
I have never direct marketed, but early on I did get an inquiry + nice offer on a 1-word that was thinking about selling but wanted to make sure I wasn't leaving money on the table, so I phoned several companies using that 1-word to see if they were interested.
Most said no, but a few others ones had some choice words for me (#%^&@!! - mostly women/Karens, surprisingly) so I never did that again, and just make due with passive sales.
P.S. I did get a second call back from a guy higher-up at one of the "Karen companies" and I'll leave it up to your imagination what I said to him.