I just came across your forum post on how to promote your vape business. I tried registering to reply to your post but my account is still pending approval so I figured it would be quicker to drop you a quick line here.
In terms of newsletter marketing, I would personally recommend the vape company email list from https://theeliquidboutique.co.uk/products/vape-company-e-mail-mailing-list
I have just received today's update and it is looking pretty good - over 39,000 clean vape company emails.
I have been using this email list with my newsletter campaigns for about 3 months and have managed to get a pretty good result for my eliquid brands.
Anyway, aside from that I would probably recommend that you build some quality vape backlinks for organic search engine rankings but this can take a bit of time. Another thing you should look at is social media marketing, especially Instagram. Try reviewing your prices and create some promotions on your site. If your products are cheaper than your competition then you would get more returning customers. Think about writing more blog posts and target a set of keywords that are important for your business.