I'm not sure how common knowledge this is, so forgive me if everyone already knows about this: Product Hunt has a feature called "Ship" that allows you to create an "Upcoming" page to begin gathering email addresses before you officially launch on Product Hunt. It's a great way to start your pre-launch phase and get a following to help you out on launch day. Obviously, the more emails you gather pre-launch, the better!
Here is what mine looks like:
Here's where you can sign up for the free tier and create an "Upcoming" page:
It's essentially a chat bot that has a short explanation of your product and allows you to begin gathering email addresses! Hope this helps!