There are a couple of ways you can do this. 

You can export your attendee email addresses from the Orders section of your dashboard and copy them into your email client of choice. For more information on exporting orders, please see the tutorial How to Export your Order Information.

Alternatively, you can connect a Mailchimp account which will automatically create a mailing list for you on that platform. For more information on how to connect your Mailchimp account to your Ticket Tailor account, please see the tutorial How to integrate Mailchimp with Ticket Tailor.