Step1: Navigate to cPanel’s Mailing Lists interface (cPanel >> Home >> Email >> Mailing Lists)
Step2: Select the mailing list and click on manage.
Step3: Click on Mass Subscription option under Membership Management.
Step4: Choose whether to subscribe to the new users now or invite the user.
Step5: Select whether to send new subscribers a welcome message by clicking the Yes or No button.
Step6: Select whether to send notifications of new subscriptions to the list owner by clicking the Yes or No button.
Step7: Enter the email address of the user below one by one in the given column.
Step8: Click on Submit your changes to finish.