So I have a mail list with crypto users and I'm sending daily mails about relevant news and the state of the market (technical analysis) but I'm wondering what else would people like. Perhaps upcoming relevant ICO's or ICO's airdrops, maybe a ''undervalued coin of the week'' with TA and Fundamental Analysis, nice giveaways?
First, check what is your conversion rate. Do people actually open the links, posts, whatever is being mailed to them? Do they flag your content as spam? And then you can think of topics that might be of most interest to them. This is more like a trial and error process. Send them emails about ICO's check the conversion rate, send emails about giveaway, check the conversion rate. You need to figure out the type of audience you've before randomly spamming their mailboxes. I personally don't like receiving any emails from the service I don't trust.