For email marketers, 2002 has been 'The Year of the Filter.'

You can optimize your creative and use the highest quality permission-lists, but most marketers are finding that their campaigns are being increasingly hamstrung by delivery problems caused by filters and blacklists.

We contacted MarketingSherpa Weekly's Tech Editor Alexis Gutzman for details on what percent of broadcast messages are affected, and why so much spam gets through when permission mail sometimes does not?

-> What percent of broadcast email is filtered out?

Gutzman says, "The truth is there is no good universal data on this - the best we have is anecdotal. Assurance Systems, which is a vendor in the field, did their own research and claim 6% of messages go into junk mail folders, but they only tested 20 email boxes."

Here are some more numbers Gutzman offered up:

* 21% of email users use desktop filtering, according to Opt-In News in 2002.

* 4% of professional marketers have their filter levels tuned so tightly that a recent MarketingSherpa test message containing almost no trigger-words was relegated to the bulk mail folder, or blocked completely, based on content.

* Percentages of the Net population with email boxes that are auto-filtered requiring little or no effort on their part (note: Numbers are not unique users. According to Valentine Radford, only 22% of online shoppers rely on a single email account).
28% use AOL
27% use Hotmail
21% use Yahoo

* Easy to implement desktop filtering options are included in lots of common software, such as Outlook, MacAfee and Norton. It is unknown how many people actually turn it on, but more Net savvy demographics often do.

* Outlook Express alone accounts for 46% of people with email boxes. When Microsoft decides to release a version with built-in automated filtering on the default settings, it would affect your deliverability to a gargantuan number of email boxes.

(Note: Outlook 11 will be configurable to restrict loading of graphics from the Internet, which makes HTML email unattractive and open-rate tracking impossible. Experts believe Outlook Express 11 will have the same functionality.)


-> With so many filters, why is s*pam still getting through?

It is the question every marketer wants to know: Why is my permission-based email being stopped at the gate when we all know pretty obvious spam gets through constantly?

Gutzman notes, more spam is stopped than you know. As of June 2002, 34% of messages going through Brightmail's networks were spam. Much of it did not hit the end-user, thanks to filters and blacklists used at the ISP and corporate-level (such as IT departments).

To understand the whole "why spam gets through" issue and how it affects your own broadcast mail delivery, it helps to know the four basic ways the big ISPs filter mail out and your solution for each one:

* Filter type #1: At the list host level.

ISPs and other large email box providers try to stop unwanted mail by rejecting anything that comes from specific IP addresses. This means they will stop all mail coming from a particular mail server, or all mail from a particular ISP, even all mail coming from a particular broadcast email list service, even if not all the mail is unwanted.

Most blacklists automatically de-list an IP address if it appears that no spam has come from that address in a given period of time. Spammers know this and switch IP addresses as soon as the one they are using is blocked.

Because blacklists list the IP address of the mail server, or the IP address block of the broadcast vendor, one bad apple can affect everyone’s chances of getting email delivered. Unlike spammers, legitimate mailers usually do not have spare IP addresses to switch to, so their deliverability is impaired as long as they are blacklisted.

Your solution is to make sure your own provider is "as pure as the driven snow and all their clients are also as pure as the driven snow," says Gutzman.

Solution: At the very least, keep a back-up email host account just in case your service is blocked. It is worth it because even the best list hosts are sometimes blocked by circumstances beyond their control. Also be sure that your current broadcast vendor makes it easy to move lists so that you can move lists to your back-up broadcast vendor at the drop of a hat.

* Filter type #2: At the header level.

Filtering software looks at all the elements of broadcast email headers. Including:
- From
- Subject
- Date
- Reply to
- Other "obscure" information in a header

Most marketers know to avoid obvious filter no-no terms in the visible parts of their email. However, the obscure parts still pose a problem.

According to Gutzman, in the past spammers infamously "broke" their headers in order to fool these filters. In the cat and mouse game of stopping unwanted email, the filters adjusted to block email with "broken" headers as well. Unfortunately that means you will be blocked if your header is broken by mistake.

Gutzman says broken-by-mistake headers are more common than you would think. Solution: Get an email expert to look at your headers as your list host sends them so you can be sure yours are fine.

* Filter type #3: The body content of your message.

If you thought filters only looked at your subject line, you were wrong. Many now view the entire message you send.

The programmers behind many of these systems do not want to stop wanted mail by mistake. They commonly devise a scaled point system that reads your whole message looking for possible-spam terms.

If the term is only used once, your message will not gain enough negative points to be filtered. If the term is used multiple times, or you have got multiple terms, your email is sunk.

Many spammers get around this by writing very short copy, so they can use forbidden terms and still get through.

Unfortunately, legitimate marketers can not always do that. Long copy tends to sell better. Newsletters with stories in the body of the letter (rather than links to read on a site) tend to be more popular.

You may lower your response rates by cutting your content enough to avoid filters.

Solution: Set up multiple email accounts using various common filters such as SpamAssassin. Then build an extra half day or more into your creative schedule to test messages and possibly test rewrites prior to sending a major campaign out.

* Filter type #4: Vox Populi.

New "peer to peer" filtering systems are launching, such as Cloudmark, in which users can vote on which email is spam and which is not. Unfortunately, what these users define as spam is often far from what the average permission-marketer would define it as.

Many simply think any email they once voluntarily opted-in for but now no longer which to receive is ipso-facto spam.

Instead of unsubscribing from your list or hitting their "delete" key, they are voting that you are a spammer. Gutzman has seen email from highly legitimate companies with strict privacy policies stopped by this.

At its root it is caused by the frustration email recipients have with overload these days. Whether from you or anyone else, it is just all too much. Far too much of it is not finely targeted enough to be perceived instantly as valuable.

The cost of cheap email just got a lot higher.