• Scrub your lists regularly.
Scrubbing your list is simply making sure that you are keeping it as clean as possible by running your list against a list of known bad domains and role accounts. While you should remove unsubscribes and relevant bounced email addresses immediately, you should also scrub your lists on a regular basis. The volume and frequency of your mailings will determine how often you want to scrub them. Scrubbing should go beyond removing duplicate addresses.

• Remove and/or correct bad domains.
Bad domains need to be removed or corrected right away. Closely review your failure reports, identify bad addresses and evaluate whether they are the result of a data capture problem or a nonexistent domain. If you're experiencing a high rate of failures, you'll want to determine how those addresses got onto your list and if they're indicative of a data capture problem. Simple data entry mistakes like misspelled domains (alo.com, hotmale.com, et cetera) can be easily corrected.

• Remove distribution accounts.
Mailing to a distribution account is never a good idea. Not only is it an unsuitable address for connecting with a customer (the equivalent of sending a letter to "occupant"), ISPs are looking for such behavior. Plus, it's also sure to facilitate spam complaints from members of the list. You can easily remove distribution accounts by adding "all," "sales," and other common addresses to your suppression list.

• Remove "spam" email addresses.
One simple step that can be easily overlooked is to remove email addresses with the word "spam" in them. These are most likely associated with spamtraps, which can lead to you getting blacklisted by ISPs or antivirus companies.

• Remove inactive addresses.
Review the email activity of your customers and compare open rates with the frequency of the email sent to them. One example might be, if you send a newsletter every two weeks and a customer hasn't opened one email in the last six months, you should remove the address from your master list. This type of program needs to be something that is specifically built around your company and your mailing practices. You can then add them to another list that is designed to reengage inactive customers with other types of communications.

• Use data checkers.
You can avoid a lot of bad addresses by putting some common data checkers at the point of data collection on your website. These checkers can ensure that the entered email address is properly formatted before it is accepted into the database. Identifying the errors at the point of entry gives you the opportunity to have users correct the mistakes as they make them. One common problem that many marketers run into is a customer entering an "!" instead of a "@" as part of the email address.