You can buy a list of email addresses, but that doesn’t mean you should do it. It can have a negative impact on your deliverability and your engagement metrics. If you only send to a bunch of recycled email addresses that haven’t actually consented to receiving your content, you won’t see the kind of ROI or customer interaction that you want.
Building your own list might take longer, but the results, in the long run, will make it worth your while. Plus, subscribers that you collect yourself will be less inclined to complain about your emails – or mark them as spam – which will help improve your deliverability.