Don't put all of your eggs in one basket as the saying goes. If you don't directly hold your contact's details, as it goes on Facebook and the like, the contacts are not yours.
I take every opportunity to invite people to sign on for my mailing list.
I hope you dont mind, but I am just going to drop a link here of your latest blog post to show how easy it is to add a call to action on a steem post to sign up to a newsletter.
https://steemit.com/dtube/@leoplaw/8vi4vwig
=D