How to Combat E-Mail Address Errors

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E-mail marketing has become a mainstay technique for winning and keeping valuable customers. Simply put, e-mail has proved better, faster and cheaper than direct mail or telemarketing for many kinds of direct marketing programs.


To conduct e-mail marketing programs, valid e-mail addresses are a must. But just as in the postal world, not all e-mail addresses on the file will be good. The sources of e-mail address errors can be genuine churn, such as when a subscriber changes Internet service providers or jobs. Or, keying errors can occur as e-mail addresses are transcribed from paper to electronic form. Often these two sources of error cause up to 30 percent of the e-mails on a previously unmailed file to be undeliverable.


To achieve the best results, e-mail address errors must be proactively remedied. The process of scrubbing and correcting an e-mail address file is known as e-mail hygiene. Let's examine the best industry practices used to combat keying errors and churn.


E-mail address hygiene may be conducted before or after transmission. In practice, the exact method will depend on what information is available and whether it's a business or consumer file. A few examples will illustrate some common techniques.


Pre-Transmission Processing


Unlike postal mail, even the smallest keying errors in the domain name or user-ID can render an e-mail undeliverable. But all is not lost. Internet e-mail standards mandate rules that all e-mail addresses must obey. These rules can be used to identify and, in some cases, correct bad e-mail addresses prior to transmission.


• User-ID. This is the part of an e-mail address that comes before the @ sign, which must be no more than 64 characters. E-mail user-IDs can contain any of the 128 ASCII characters, except special characters, such as semicolons, parentheses and left and right angle brackets (<, >); control characters, such as line feeds and carriage returns; and spaces. If these special characters are detected, transmission is suppressed and correction is attempted.


Internet e-mail protocol sometimes allows the existence of user-IDs to be validated prior to transmission, using a command called SMTP Verify. However, it is sometimes easier to just attempt delivery, rather than check each address beforehand. System administrators have the ability to disable support for this feature, making it impossible to confirm the existence of a valid e-mail address.


• Domain name. Both top-level and secondary domain names -- the part of the e-mail after the @ sign -- may be validated before transmission. A first step is to check that each e-mail address has a valid top-level domain, and attempt fuzzy matching on a table of allowed values to correct any errors.


Post-Transmission Processing


• Categorization of bounces. Undeliverable e-mail addresses generate a return error message called a bounce. Bounces disclose the reason the e-mail was undeliverable. Common reasons include a bad user-ID, a bad domain name or a transient network or server problem. This information can be used to focus e-mail address correction efforts.


• User-ID. Bad user-IDs associated with consumer e-mail addresses are usually difficult to correct. Business e-mail user-IDs may sometimes be corrected using standardization techniques that make it possible to infer the naming convention used at a given domain. This technique works for medium- and large-size businesses - 35 percent to 45 percent match rates can be achieved, and results as high as 70 percent sometimes can be obtained.


• Domain name. Consumer e-mail addresses should contain one of 7,000-plus ISP or free e-mail domain names. Fuzzy matching of the bad domain name against this list often corrects the most common "off-by-one" keying errors.


Many businesses register their own domain names in lieu of using an e-mail address associated with an ISP, such as mybusiness@aol.com. The name/address of the business can be linked to a domain name by public sources such as the InterNIC registry, www.internic.net. Match rates as high as 75 percent can be obtained for files comprised of medium- and large-size businesses.


Addressing Churn


Up to now, we've outlined a regimen for addressing e-mail address keying errors. But churn is also an important cause of undeliverable e-mail addresses. Unlike postal mail, no National Change of Address file exists to track churn in e-mail addresses. As a result, two other techniques are commonly used to address churn.


• Integrated data collection. Perhaps the best approach to fight churn is to constantly gather e-mail addresses on an opt-in basis from your clients through direct mail, telemarketing or Web site contact.


In some instances, targeted data collection can be initiated. When bounce classification identifies a bad user-ID (assuming e-mail has previously been successfully transmitted to the same address), permission-based telephone or direct mail contact can be used to collect the new address. Often, a small incentive is provided to respond.


• Data enhancement. At present, commercial databases/enhancement services are being developed to address market need. These databases have no more than 15 million records, with typical match rates of only 2 percent to 5 percent. However, within the next 12 months to 18 months these services will likely achieve a critical mass of records and better match rates will result.


E-mail address hygiene can be a useful tool for direct marketers. Today, e-mail address hygiene relies largely on ad hoc techniques to correct keying errors. But as better e-mail databases are constructed, Internet marketers will have access to tools that rival their postal counterparts.


• James Green is president of the technology solutions division of 24/7 Media Inc., New York. Reach him at james.green@247media.com.
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