Getting someone to take an interest in what you are promoting is just the start. These
valuable people need to be nurtured through follow-up emails.
When you are starting out you can just about do this manually - say 20 or so email addresses
But as things grow you really have to get an account with an 'autoresponder' - that is a service which stores your email list (which is added to), as well as a series of emails which are generated automatically and sent out at intervals determined by you.
You can, of course, send out a newsletter (broadcast email) to all email addresses in your list
which can be stored by your webpage host.
Whatever you choose, just do it. You will be glad you did!