You can find the Email list ID by following the steps below.
1. At the top of your Dashboard page, hover your mouse over the Audience tab to reveal the drop-down menu, and then click on the Email lists option.
2. Click on the name of the email list, the Email list ID of which you wish to find.
3. The Email List ID will appear just below the name of your email list, on the left top corner of your page.