March 05, 2013, 8:32 PM — Spamhaus is warning marketers to keep their databases cleansed of bad email addresses lest their messages be mistaken for spam and blocked.
The U.K.-based spam-fighting organization had taken some heat for blocking so-called "transactional" email messages, or messages a retailer sends after asking a consumer if they want to receive a purchase receipt by email. The practice allows retailers to grow their email marketing databases.
But the problem is the email address is often incorrectly typed in. And if a retailer begins to send other messages to the address -- especially if an address is invalid -- it can start to look like spam.
Spamhaus publishes data that is used by email service providers to block IP addresses that have been known to deliver malware or spam. In December, Spamhaus blocked some email from major retailers such as the Gap and Gilt, according to Ken Magill, who edits an industry marketing newsletter.
The issue isn't so much a one-off receipt that goes to an invalid email address or a typo that causes the email to go to an unintended recipient. What sets off red flags is when a marketer continues to send email, even when they receive a "bounce," or a notification that the email address didn't accept the message, wrote Denny Watson of Spamhaus.
"If the email stream is persistent over time, especially high volume, and drifts outside the relationship of individual transactions, we may find these messages a problem," Watson wrote.
Overall, those kind of messages waste mail server resources as well as annoying third-party recipients, he wrote.
"The ongoing flow of presumably unintended bulk email from unattended mail systems operated by well intentioned but careless senders is unsolicited bulk email (spam)," Watson wrote.
Being blacklisted by Spamhaus can negatively affect marketers, wrote Chris Kolbenschlag, the director of deliverability at Bronto, a company that develops software for email and social media campaigns. One way around the problem is to send recipients an email asking to validate their email address and grant permission for future messages.
Email addresses that do not return those messages should then be removed from databases, though Kolbenschlag acknowledged the practice isn't popular. But in the end, marketers can then remove potentially incorrect addresses and keep themselves off blacklists, he wrote.