5 Things Marketers Should Know About Spam Filters

Sometimes context means everything. Especially when an e-mail contains "XXX." So while Super Bowl fans may have found messages from the National Football League innocuous, spam filters did not. The filters didn't bother to understand the concept of Roman numerals that counted out the games between 30 and 39. So e-mail experts did, and here they provide more tips for marketers in similar fixes.

"As you might imagine, 'XXX' lights up like a Christmas tree," says Rick Buck, director of e-media and privacy/ISP relations for e-mail service provider e-Dialog, headquartered in Lexington, Mass. "Back in the early days, when spam filters were just coming into the horizon, that became a real problem for [the NFL]. But the good news was the spam filters pointed it out ... [and] we were able to figure out ways to optimize the creative in such a way that [the] image could be shown without showing up as something that would be blocked by spam filters."

While some marketers may believe those bad old days are gone, those who work in the e-mail space say that's both true and false. Content filtering is back, they say, and is included in the important knowledge marketers should have about spam blocking systems.

1. The filters need to see a valid domain key so they know the e-mail's return path is real. "First thing [spam filters will] do is take a look at your sender address, and they'll take a look to see if there are e-mail header technologies involved, such as DKIM and SPF," says Aaron Smith, a principal with Seattle-based e-mail marketing strategy and creative services agency Smith-Harmon. "These authentication mechanisms serve as a sort of handshake so that the server can actually go to a very specific location and say, 'Oh, OK, yes. This really is a server.'"

2. Do a good job of managing sending IPs in order to maintain a good reputation. Relationships with spam filters do matter to a sender's reputation, but spam filters factor in that reputation, too, Buck says. So to stop that never-ending circle from spinning, he recommends that marketers also pay attention to list hygiene, bounce rates and complaints. "If you're focused on doing all of the right things in the first place ... you almost won't have to worry about [the spam filters]," he says. "Because you're going to have a great reputation, because you're going to minimize your bounces, and complaints and minimizing your bounces and complaints, frankly, keeps your IP reputation up. If your IP reputation stays up, that's also part and parcel because your creative is good, because your copy is good, because your audience is good, because your message is good."

“It's harder to be relevant and interesting, but it pays off handsomely
in higher revenue,” says Stephanie Miller, vice president of market development at New York-based Return Path, an e-mail performance management company. She cites the example of a dating site that “significantly reduced complaints by offering choices on frequency and adding a bit of helpful advice to alerts that went to less active members.”

3. Marketers should check their spam credentials. For the most part, ISPs aren't going to tell marketers if their messages are getting tossed as spam because they don't want the "bad guys" to find out how they're judging the e-mails, say Buck and Smith.

When 95 percent or more of a marketer's e-mails are being delivered, that's good, Smith says. Senders should worry when that drops to around 70 percent or 80 percent, he says. E-mails in the latter percentage, even if there aren't any bounceback messages, may not be arriving in inboxes, he says.

ISPs dumping e-mails without telling senders is called "black holing," and it's more common than marketers think, says Jordan Cohen, senior director of industry relations for e-mail authenticating firm Goodmail Systems of Mountain View, Calif.

Buck, Cohen and Smith say marketers can review their ratings on sites like Spamhaus, which identifies spamming IPs; SpamAssassin, which has a program that rates e-mails according to how "spammy" they are; and through services like those of Return Path and Phoenix-based Pivotal Veracity, an e-mail delivery service provider.  

4. E-mail content should be designed with spam filters in mind, especially in the case of business-to-business copy, but still may be allowed to contain iffy keywords. Back to the XXX example, Buck says marketers should run their creative through spam filter tests before editing out questionable keywords. They may be able to stay, depending on the e-mail's context—including whether the sender is already in the recipient's address book, if the IP has a good reputation, if the sender is authenticating its e-mail and if it's certifying its e-mail through companies like Goodmail.

"That changes a little bit when you look at the B-to-B space," Smith says. "The filters being used at most corporations tend to be a little bit further behind in terms of advanced filtering systems ... you do need to be more concerned with content."

5. Allow time to warm up any new servers, which may be necessary when switching e-mail service providers. Cohen says volume triggers vary, depending upon domain, and they can be set off by mass mailings from new IPs. Often, ESPs take care of this need in-house, he says. But sometimes that doesn't happen. Cohen points to a client that didn't send out a few e-mails to establish its reputation on its new IP (the client had an excellent reputation on the old one) and got 20 percent of its mail blocked by AOL. "You need to have a pre-existing reputation in order to get delivered."

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