A growing frustration among professional e-mail users is the fact that much of what they send, may very well never be delivered. While many are aware of this problem, few realize how much legitimate e-mail is being blocked, and why.

For the most part, failed e-mail is primarily the result of attempts to cut down on the amount of junk email (SPAM) that is being sent today. Such efforts to reduce unwanted e-mail by Internet Service Providers (ISPs), companies and even individuals all have such unintended consequences.

Road Blocks Ahead

When a legitimate e-mail is blocked from delivery, this is referred to as a false-positive, as the message was falsely labeled as SPAM, and blocked as a result.

When it comes to false-positives, the biggest offenders are systems that rely on commonly available e-mail "Blacklists" which have been show to have false-positive rates as high as 34 percent. Unfortunately, many ISPs, companies and even individual anti-SPAM software programs use such Blacklists.

My own ISP is ATT, and its servers are often erroneously blocked by such "Blacklists." When this happens, all e-mail originating from the entire ATT network can be blocked as SPAM.

Another problem with "blacklists" is that if you have a Web site hosted on a "shared server" (this would apply to almost every agent Web site, and most company sites, as well) and another site on the same "shared-server" is "Blacklisted" as a known sender of SPAM, then your e-mail will likely be blocked by many ISPs simply because your site is on the same server as the offenders.

Final proof that mother was right: You ARE known by the company you keep, even if you don't know them!

While many ISP's now use filtering technology that goes beyond simple "Blacklists," these systems still often have false-positive rates in the 6 percent to 8 percent range. While better than relying on "blacklists" this is still a lot of legitimate e-mail that's being blocked.

Another issue is the growing number of anti-SPAM software programs that can be used by individuals. These programs tend to have false-positive rates in the 2 percent to 8 percent range, and that's for the best of them, and only when the user is skilled in their implementation, configuration and maintenance of such programs.

Further, the e-mails that are blocked by desktop software programs first have to survive the filtering processes used by ISPs, so the effective false-positive rate is likely much higher.

Finally, many users and anti-SPAM programs rely on simply keyword filters that will result in a great number of false-positives, as well. While most users don't consider all of the ramifications of their filters, it's important to realize that even the most obvious words that you might think of blocking all likely have legitimate uses.

For instance, a subscriber to my Canale's Tips & Tricks newsletter recently related that all e-mail from me was being blocked because their anti-SPAM filter misread my name and interpreted it as cANALe which, understandably, seemed like a good candidate for their banned word filter at the time.

The bottom line is that when you send e-mail, its delivery is at the mercy of:

• Blacklists that block up to 34 percent of e-mail
• ISP filtering that knocks out another 6 percent to 8 percent
• Desktop software that will remove another 2 percent to 8 percent
• Keyword filters that may remove another untold percentage of legitimate e-mail

The lesson: Just because you send it, don't assume it was delivered!

Further, and maybe of greater importance, be very careful about the anti-SPAM solutions that you personally implement (as well as those used by your ISP) as you are probably blocking legitimate inquires from customers, clients and prospects alike.

In a best case scenario, even blocking just 2 percent of your business leads could cost you a small fortune!