With a few lines of ASP code, you can let users send email directly from your Web site, survey their interests, and track people who want to be on your mailing lists.

So you want to know who's been visiting your Web site, do you? We'll not only show you how to track who came to your site, we'll also show you how to track why they came and what brought them there. We'll do this by demonstrating how to email-enable a Web site to send comments, questions, and survey information from a site's visitors to the Web administrator. We'll even track which users want to be on our email distribution list so we can contact them with periodic promotional offers and other information.       The Visitor Tracking application is a simple but powerful tool that we employ on our Web sites to allow visitors to better interact with us. It can also allow you to closely track specific areas of interest by asking visitors to fill out a very short but useful survey. There are some key pieces of functionality that you must master before you can implement such a site, including sending email across the Internet. Introducing CDONTS       If you're looking for an easy way to send email over the Internet from your Web pages, look no further. Collaboration Data Objects for Windows NT® Server (CDONTS) and Simple Mail Transfer Protocol (SMTP) provide the interface and the means to send email from Active Server Pages (ASP) with only a few lines of code. The objects that comprise CDONTS are actually packaged with SMTP, so when installing the Windows NT Option Pack for Windows NT Server, you'll have to choose to install SMTP to get CDONTS. If you have had any experience with writing an email-enabled application, or even just trying to send email from a program, it probably hasn't been a good one. MAPI, the earlier standard, isn't exactly straightforward, so you won't be surprised that we are going to lead you away from that interface and steer you toward CDONTS.       CDONTS has a robust interface to send, read, and even generate attachments. We are going to concentrate on a single object within its interface: NewMail. The NewMail object gives you the basic functionality to send email, such as the To, From, CC, BCC, Subject, and Body properties and the Send method. There are a few tricks involved with sending email using CDONTS, but they are simple to code around once you are aware of them.       Let's explore how you can take advantage of the CDONTS.NewMail object through the Visitor Tracking application. The full CDONTS object model incorporates extended features that can't be comprehensively covered in this article. First, we're going to show you what the Visitor Tracking application does from a user's standpoint. Then we'll explain the code and show how to integrate CDONTS into it. So grab a can of pop and a bag of chips and read all about how the CDONTS.NewMail object can be used in your own The Visitor Survey       We set up a survey page that captures each visitor's information in a database (see Figure 1). This information is sent to an administrator, and a confirmation email is sent to the visitor. We can track any information gathered on this page, but we'll keep it simple here.

Figure 1: Web Survey Page

As you can see in Figure 1, the visitor is interested in finding out more about our training classes and consulting services. She has also specified that she is interested in how we could help her develop an online shopping cart application for her company. Once the visitor clicks the Send button, this information is stored in a database for the Web administrator to review. Email containing the information is sent to the Web administrator, and the user is also sent email, confirming the successful submission of the survey.

Figure 2: Viewing Survey Results

We decided to store the user's survey information in a database so we could keep the information in a more permanent form than email. This choice also allowed us to track the visitors that come to our site, how often they come, when they come, what they have to say, and so on. Figure 2 shows how you can view the results of the visitors' surveys.       We set up several options to view the results. Read Mail lists the chosen surveys, Read All lists all the surveys, Read New lists only the new surveys, and Send Mail sends email to all visitors who have joined the distribution list. If we click on the Read New button, we will only see the new surveys that haven't been reviewed (see Figure 3). If we want to see a survey's details, we can simply click on the visitor's email address. We could also delete the surveys by checking the Delete checkbox and clicking the Delete button.

Figure 3: Read New

From this interface, we're able to send a message to our entire distribution list of willing visitors. Remember that the visitors were allowed to specify whether they'd like to receive any email when they were on the survey page. If we click on the Send Mail button, we go to the mass email page. Here we can enter a subject, the from address to be used on the email message, and, of course, the message body itself (see Figure 4).

Figure 4: Mass Email Page

This application relies on email to communicate, but it also takes advantage of a database to store the surveys in persistent form. In fact, we could easily query the database on how many visitors inquired about our training services. Of course, the more extensive the survey, the more powerful the Visitor Tracking application becomes. Now that you've seen the application, let's take a look at the code. Go to the Code       We think you will be impressed by the simplicity of the code (this ain't brain surgery) and the scalability of the application. Once you see the code, you'll be thinking of how you can morph it to fit into your applications. Let's dig in by looking at the code for the Survey page.       The Survey.htm file (see Figure 5) captures the visitor's information and submits it to the Thanks.asp file. There is a little script included in this page. Figure 6 show the script included by Survey.htm that validates the visitor's input. The code in Figure 6 simply makes sure the visitor enters their first name, last name, and email address so we can get hold of them. We used server-side scripting code to make sure this Web application could be used on most browsers.       The Thanks.asp file (see Figure 7) takes the data submitted by the Survey.htm page and disseminates it among the database and email recipients (the visitor and the administrator). First, we declare all of our server-side variables and use the Request object to retrieve the form values that were passed from the Survey.htm page. Then we translate the checkbox values from the Survey.htm page to either a 1 or 0, representing on or off.       Next, we declare the ADO Connection and Recordset objects and open the database connection using the system DSN we created. (We called ours CDONTS, but the name is arbitrary.) Then, we check to see if this particular visitor has visited our site in the past (based on their email address). If not, we insert the visitor's name, email address, and whether they want to be on our distribution list. If this is a repeat visitor, we check to see if their distribution list status has changed. If so, we toggle the distribution bit in the database using some more SQL. Finally, we insert the survey results into the Visit table, send email to the visitor confirming their visit, and send similar email to the Web administrator.       Sending the email messages only takes a few lines of code, as this excerpt shows:

'——————————————————————————————— '— Send out the email to the visitor '——————————————————————————————— set objEMail = Server.CreateObject("CDONTS.NewMail") objEMail.To = strEMail objEMail.From = "info@bluesand.com" objEMail.subject = "Thank you for your inquiry." strBody = strFirstName & "," & vbCrLf & vbCrLf & vbTab strBody = strBody & "Your information is being processed." strBody = strBody & vbCrLf & vbCrLf & "Thank you, Blue Sand Software." strBody = strBody & vbCrLf & vbCrLf & "http://www.bluesand.com " objEMail.body = strBody objEMail.send set objEMail = nothing

First, we create an instance of the CDONTS.NewMail object using the Server.CreateObject method. Then we set the To, From, Subject, and Body properties to their appropriate values. Finally, we issue the Send method to send email to the recipients, and then destroy the instance of the object. Here is where it gets a little tricky.       The CDONTS.NewMail object's properties are designed to be write-only, single use. You can't read their values, and you can't overwrite them after you use them once. For these reasons, we can only use the object for a single email message. This is why we create a brand spankin' new NewMail object to send to the administrator. Don't get us wrong—you can send email to more than one recipient at once, but you can't reuse a NewMail object by putting it in a loop and changing the To property each time. To send mail to multiple recipients, you need to create and destroy the object each time. This is actually how we handled mass emailings, such as distribution lists—but now we're getting ahead of ourselves. We'll get to this topic a little further on. At this point, it is important to understand the basic properties and methods of the NewMail object.       There are two pages that send the mass email messages to visitors on our distribution list. MakeMassEmail.htm (see Figure 4) submits its form data to SendMassEmail.asp (see Figure 8). Again, we create our ADO objects and connect to the database. Then we loop through the list of visitors that are on our distribution list. It is within this loop that we create the CDONTS.NewMail object, set its properties, send the email, and destroy it before we do it all over again for each visitor.       We could have used some other properties of the NewMail object to get the job done without continually creating and destroying the NewMail objects. Instead, we could use the BCC property to specify the email addresses of the visitors, separated by semicolons, as shown in the following excerpt:

Dim strCC set objEMail = Server.CreateObject("CDONTS.NewMail") objEMail.From = Request("txtFrom") objEMail.Subject = Request("txtSubject") objEMail.Body = Request("txtBody") do while not objRS.EOF strCC = strCC & objRS("EMailAddress") & ";" objRS.MoveNext loop objEMail.CC = strCC objEMail.Send set objEMail = nothing

This code is much more efficient in that it does not have to continually create and destroy the NewMail object. It does have some side effects. First, the recipients will not see an email address in the To field of their email. Also, you can't personalize email when you send the same message to everyone. These are minor setbacks that are usually acceptable. Keep in mind that we would probably not want to set the To property to specify all of the recipients. If we did, all of the recipients would see the other recipients' email addresses. Most people consider that an invasion of privacy. In large mailings, it also inflates the email's size drastically—what would have been a 1KB message can inflate to several hundred KB per person depending on how many names are listed on the To line. Most people really don't appreciate getting 500KB mail with only a few lines of content. Summing it Up       Using the CDONTS.NewMail object is an easy and powerful technique to solve the problem of email-enabling your Web applications. You can even attach files to messages using the AttachFile method. This is a quirky solution because developers using Windows® 95, Windows 98, and Windows NT Workstation cannot utilize these features on their workstations. To access AttachFile, you must have access to a Windows NT Server because CDONTS relies on the SMTP service to do its duty. This is usually an OK, but annoying situation.       In fact, all mail that CDONTS sends goes through the SMTP service on the Windows NT Server box. CDONTS actually formats the email into a text file and places it in the Pickup folder of the SMTP service for delivery. You could create your own text file in the appropriate format and place it there as well, but why bother when CDONTS will do the dirty work for you?       Another issue that we have found is that the From property must be specified. The content of the From property doesn't seem to matter, as long as some sender is associated with the email. This differs from the documentation, which states that you can omit the From property. This brings us to another point: most errors with CDONTS do not actually generate an error. This is somewhat understandable as most errors are due to inaccurate email addresses. So be sure to check them periodically for accuracy.       With all of its little quirks, I wouldn't trade in the CDONTS.NewMail object for the old emailing methods. CDONTS is simple to learn and easy to use. What else do most programmers need? But if you need more functionality than the NewMail object provides, you can tap into the extended object model of CDONTS that allows you to receive email through SMTP as well. But for simple outgoing messaging, the NewMail object gives you an edge. So leaf through the code, which you can find at the link at the top of this page. We're sure it will come in handy! See the sidebar: SMPT

From the February 1999 issue of Microsoft Internet Developer