Identify and Remove Invalid Emails: Use an email verification tool to identify and remove invalid addresses that could harm your deliverability. Remove Inactive Subscribers: Determine a criteria for inactivity (e.g., no opens or clicks in the last six months) and remove or attempt to re-engage these subscribers. Check for Duplicate Entries: Ensure each subscriber is only on your list once to avoid sending multiple emails to the same person. Update Contact Information: Allow subscribers to update their preferences and contact information to keep your data accurate.