Question: How can I keep my e-mail list clean? Answer: You'd be forgiven for believing that the size of your e-mail list carries more weight than the quality of the e-mail addresses it contains. Truth is, sending messages to inactive or invalid e-mail addresses causes nightmarish problems for your sender reputation. Now more than ever, thorough e-mail list hygiene is a good habit that all e-mail marketers need to adopt if they want to stay ahead of their game. Here are four quick ways you can help keep your list clean and shiny. 1. Honor unsubscribe requests, removing them as soon as possible from your list. It really is better for both you and the subscriber at the end of the day. You won't continue wasting your money sending e-mails to people who aren't interested, and they get to bow out gracefully. 2. Address any hard or soft bounces immediately. A hard bounce is likely due to an invalid or nonexistent e-mail address, in which case you can easily verify it. Sites such as verify-email.org and email-unlimited.com offer simple, free e-mail verification and test the format of the e-mail and the validity of the domain and user. Also keep an eye on soft bounces and remove any subscribers that haven't opened e-mails from you in more than 6 months. Keep all inactive e-mail addresses together so that you can target them later with an exclusive reactivation campaign. 3. Check your list manually. If your e-mail list is small enough, you can check it manually for simple data entry mistakes such as misspelled domains (e.g. hotmale.com and alo.com). Once they've been corrected then run them through the e-mail verification tool again. If they come back with an error after this, then discard them. 4. Make use of data validation on your subscription form. By validating each field, you can ensure that any information entered is formatted correctly before it is accepted into your list. Visitors can correct their mistakes immediately, which saves you the trouble of having to do it later. Depending on how fast your list grows, you should make a point of regularly sifting through it every six months. This way you can rest assured that it will remain clear of any spam trap-luring e-mail addresses. Plus, you'll also save yourself money and trouble in the long run. Georgia Christian is the editor of online e-mail marketing service Mail Blaze (www.mailblaze.com). Question: How is user engagement affecting e-mail deliverability? Answer: Previously, Internet service providers looked at three particular metrics when assessing the legitimacy of an e-mail sender: 1) How dirty the list is: Are a lot of invalid e-mail addresses being targeted? 2) Spam complaint volume: How often do subscribers hit the “Spam” button? 3) Content: Is the offer spam? This notion has been turned upside down. AOL Google, Hotmail and Yahoo earn more revenue from engaged consumers; the more ads served up that match consumer preferences, the more revenue each subscriber generates. As a result, it's crucial for such companies to ensure that their e-mail offerings are engaging for their audience, so they are now examining the following: 1) How many people open an e-mail? 2) What percentage of the people who open an e-mail click on the links? 3) How many of the e-mails are forwarded? Google is taking this one step further by putting the best performers in the most prominent position as part of its Priority Inbox offering; Google's algorithm makes predictions on which e-mails are important to the receiver based on e-mail history. Those that are regularly opened and/or responded to will be sent to the Priority Inbox, and according to Google, the determination is made based on “who you've e-mailed and chatted with most and which keywords appear frequently in the messages you opened recently.” This is all the more reason to ensure your e-mail marketing campaign is engaging the subscriber. If your e-mail is generating lower open and click-through rates, revamp your campaign so that it resonates with your audience. If not, be prepared for your e-mails to end up in the “everything else” part of the inbox with the rest of the e-mails that go unnoticed and unopened. John Murphy is president of ReachMail, a provider of e-mail marketing services, solutions and advertising.