Making the mailing list of any site is very necessary. With these mails you send the updates to the people. With emails you also send the new offers to the people. Emails are also just like social media. As you give the updates to the people with social media, the email also works just like this. With the emails you can contact directly with subscribers. Those who like your blog they become your subscribers.
If you also want to make email list for your website you also add the subscriber button in your website.
You will find many email list online by which you can work. But they have a problem. The problem is that it might be possible that many emails out of those may not be related to your topic. Possibilities are that many of them might be dead and only few are active.
If you get from somewhere 1000 email list possibilities are only 10-20 of them might be of your use and the rest might be useless. So always ignore such kind of lists. Make your own list.
There are many mass email sender software by which you can send the email to all of them simultaneously.
There are many online list provider which provide you list.