Identify Inactive Subscribers: Use your email marketing platform's analytics to identify subscribers who haven't engaged with your emails for a specified period. Send Re-engagement Campaigns: Attempt to re-engage inactive subscribers with a targeted campaign. If they still don't respond, consider removing them from your list. Remove Hard Bounces: Immediately remove email addresses that result in hard bounces, as these are permanently undeliverable. Verify Email Addresses: Use third-party tools to verify the validity of email addresses in your list.