Most e-mail marketers already know how to build a quality, permission-based e-mail list, but many don't realize how quickly those shiny, new lists can become messy, clogged and ineffective. If your e-mail hygiene is lax, you're greatly limiting the success of your campaigns. An up-to-date, clean e-mail list can have a big impact on your delivery, open and clickthrough rates and your ongoing compliance with CAN-SPAM laws.
Perhaps you think your e-mail list is clean enough. Well, consider this: 50 million people changed their e-mail addresses last year. How many of those abandoned e-mail addresses are on your e-mail list right now? If you don't know, perhaps it's time for a checkup.
Your e-mail list was built with honest effort and good intentions. Don't let your recipients' actions or inaction negate your work. If they don't notify you when they change e-mail addresses, it could be that they no longer wish to receive your e-mail communications, or they just forgot. Either way, those inactive addresses decrease the effectiveness of your list. Now, it's up to you to get them off your list.
Add to that this very important point: Permission is perishable. Just because you received permission to send e-mail messages to someone six months ago, it doesn't mean he is still interested.
Don't let a messy list impede your success. Follow these steps to polish up your e-mail list:
1. Analyze bouncebacks. After every e-mail campaign you send, analyze the bouncebacks you receive. Identify the different reasons for the bounce — such as your e-mail was blocked or the recipient is no longer at that address — to determine next steps. Remove hard bounces from your list. This is also a great way to identify and correct obvious typos in your list, such as ".con" instead of ".com."
2. Manage your unsubscribe requests. If you use an e-mail marketing service with automatic unsubscribe, this step is handled for you. If not, do this yourself. Not only does it help you maintain a clean list, but it's also required by law.
3. Monitor your "reply to" address. Many recipients are fearful of using the unsubscribe function since it has been used by spammers to verify an address rather than as a legitimate unsubscribe. So, be alert to unsubscribe requests coming to your "reply to" address and permanently remove those e-mail addresses.

All About Email Creative