We were drowning in email spam. This spam is expensive. It was clogging our email servers. Our networks and desktops were vulnerable to all sorts of nastiness that could enter our computing environment when the email was uncontrolled. Because it is out of control, we were determined to do something about it. Therefore, we have adopted rigid and discriminatory sentries to our public email face and we are now more self-assured that we are practicing safer computing.

Unfortunately, many others have also pursued this route to sterilizing their email. Now we are learning the second side of the protectiveness. Our email is not reaching its target and even when we think it is, we are uncertain if it has. We wonder why a recipient has not responded to a specific request or issue. We become almost neurotic about following up important emails with phone calls or faxes. The value of the instantaneity of email and its usefulness is diminished by the attack on email's reliability. What are we to do?

James A. Froude, a Nineteenth Century English historian, whose words I began this column with ring true. The evolution of email usability in the context of threats to its certainty of reaching a destination is evolving. The biggest email mistake was assuming that no one would misuse email. Now, AOL, Microsoft, and many of the major Internet Service Providers (ISPs) are investigating and negotiating on developing better ways to assure that a sender of a message is who he says he is. In the meantime, let us examine what to do until then.

Why is email not being received?

Mail can be blocked in many ways including one or more of the following ways:

• The send button is never actually pressed. Never dismiss this possibility.
• Occasionally, ISPs will suffer temporary technical problems that prevent them from being able to deliver to a valid email address. This is most common during peak usage hours when an ISP's email infrastructure is being overwhelmed by too many email messages. This could be the ISP on the sender's or recipient's side.
• Your ISP has limited the number of recipients who may be copied on a single message from your domain.
• The recipient's ISP has somehow blocked all mail coming from the sending ISP, our domain, our sending IP address (the numeric representation of the sender's home on the Internet), or an individual email address representing a specific complaint about the specific sender.
• The recipient's email may be spam filtered by one of the major outsourced filtering companies on the way to the server serving up the mail. Some examples of such services include SpamStopsHere (SpamStopsHere.com), Postini (Postini.com), and MessageLabs (MessageLabs.com).
• The recipient's email may be spam filtered by the server serving up the mail with an internally hosted anti-spam software or even hardware/software appliances. 
• In the email client (i.e., Microsoft Outlook) being used, the recipient may have indicated that the sender or specific attributes of a subject line comprise spam.
• Subconscious filtering where the recipient quickly goes through the in-box and deletes messages without ever opening and reading contents based on sender, subject line, or simply by mistake.

Automated filtering often is often not limited to sending address, sending source, or even topic aversions. It can be other message attributes that flag a message such an attachment type, formatting of the email, frequency of receipt from a sender, message size, or volume. While the others are self-explanatory, volume is a bit unusual. The volume-based threshold may be defined as bandwidth, messages per second and/or number of simultaneous connections from a given server. The volume-based thresholds differ between ISPs and are not public knowledge. Volume-based filters have nothing to do with a particular message being spam. Rather, it is a way for an ISP to protect itself from high volume demand from a particular sending source or, worst yet, some sort of nefarious email-based attack.

What to do about blocked mail or how to avoid being blocked?

There is no panacea to being blocked. Before addressing some ideas to reduce the likelihood of being blocked, let me set some guidelines. Abide by the provisions of the law with all email that you send. This includes CAN SPAM Act of 2003 as well as more local ordinances about what constitutes spam and how to protect the recipients who do not want to continue receiving it. When generating mass email campaigns, use opt-in and opt-out options. Avoid turning any email effort into a recipient's spam experience.

To reduce your likelihood of having a message filtered out, some things to avoid include:

• Sending an email to more than 50 or 100 addresses using your email client using either TO, CC, or BCC. Use blast email services for legitimate mass emailers like Constant Contact (ConstantContact.com) and RealMagnet (RealMagnet.com) for these types of email.
• Sending extremely large attachments or attachments with usually suspicious file types like EXE, JPG, TIFF, SCR, VBS, etc.
• Sending out a HTML-only formatted messages. Instead send messages using plain text format or dual HTML and plain-text.
• Keeping bad or bounced email addresses as recipients of your emails.
• Sending emails to recipients that include any spam flag addresses like postmaster@AOL.com.
• Using the word "Free", CAPS or excessive use of punctuation marks in the Subject line.
• Leaving the subject line empty. 
• Overusing color in HTML mail.

Email provides more intimate contact to many of us than does paper mail. We must appreciate and not abuse this privilege of contact. Still, being aware of and avoiding some of the behaviors above will result in increasing our effectiveness with this valuable tool. Our reliance on email will not diminish; we must be committed to not only keep the riff raff out of our email, but to allow valid messages to reach us.

CHAIM YUDKOWSKY, CPA, CITP, is Director of IT for the American Israel Public Affairs Committee (AIPAC) based in Washington, DC. He is also president of Byte of Success Inc., a technology consulting company specializing in helping small and mid-size business grow using technology. He is available for both consultation and speaking. He may be reached at cyudkowsky@byteofsuccess.com.