Turning cold email list into opt-in

Dunno where this should go, but as this stuff is borderline legal I guess BHSEO works

Anyhow, I'm currently working with email marketing "campaign" where I ask people to email me on open forums and then take the discussion from there. Needless to say I get hundreds of unique users emailing me every day and I make tons of conversions from those alone. However I was thinking that I'm currently able to combine quite massive (target country wise) mailing list of highly targeted users that are more or less interested in what I have to offer, so could I maybe use this collected info to send them an "invitation" to VIP newsletter or something along the lines, and then with the opt-ins mail offers in the future?

I get that my current list is not really suited for direct marketing, but would it be a complete waste to try to lure them in with e.g., free stuff that I'd send them 2-3 times a month?

Worst case scenario I'm out of few bucks that I've spend for the mailing, best case scenario I' be making tons of cash for a long period of time - but is it still a good idea?

Yes Id definitely create some form of squeeze page to get them join your list 'officially'. When interacting with people just build up a bit of trust and then throw a line in saying something like 'Hey, Im really pushed for time right now but if you go to this page and leave your name and email address I can get back to you shortly, I'd also like to give you a copy of my free guide as an apology'

I know it's not perfect but you get the picture! but building a double opt-in list is well worth it!!

Get a nice email design, buy host and domain and do a nice squeeze page to opti in with some pretest, while tryin to get authority with your clients, and then when you collected enough mails start to send out 1 freebie alternated to 1 paid product