E-mail is often a standard part of Web-based
applications. You may use it to send logon information to users or
even to send error messages to application administrators. ASP.NET
makes it easy to utilize e-mail in an application with the
System.Web.Mail namespace. Let’s take a closer look at putting this
namespace to work in your applications.

System.Web.Mail namespace

The Microsoft documentation provides a good
overview of the System.Web.Mail namespace. It’s composed of classes
that allow you to create and send messages using the Collaboration
Data Objects for Windows 2000 (CDOSYS) message component. The
actual message may be delivered via the SMTP (Simple Mail Transfer
Protocol) mail service built into Microsoft Windows 2000 and beyond
or through an arbitrary SMTP server. The classes in this namespace
aren’t restricted to an ASP.NET application.

The namespace includes three classes:

  • MailAttachment: Provides properties and methods for constructing an
    e-mail attachment.
  • MailMessage: Provides properties and methods for constructing an
    e-mail message.
  • SmtpMail:
    Provides properties and methods for sending messages using the
    CDOSYS message component.

MailAttachment class
The basic approach is the creation of a MailMessage object
followed by sending it on its way via a SmtpMail object. The
MailMessage class contains numerous methods and properties for
working with an e-mail message. Properties such as From, Subject,
and Body provide everything you need to create an e-mail message,
but a SmtpMail object is still necessary for sending it on its
way.

SmtpMail
class
The SmtpMail class includes the SmtpServer property that gets
or sets the name of the SMTP relay mail server to use to send
messages, and the Send method actually sends the message. The Send
method is overloaded. It allows a message to send using two
approaches:

  • A MailMessage object is passed to the
    SmtpServer object.
  • Four string objects may be passed to the
    SmtpServer object with the first being the From field followed by
    the Recipient, Subject, and the message’s Body.

You’ll use the MailAttachment and SmtpMail
classes together to create the necessary messages in your
application, but make sure the Web server is properly configured to
send a message via SMTP. Since IIS (Internet Information Services)
is the most popular platform for ASP.NET applications, go ahead and
use both the IIS and SMTP services to send messages from your
application.

Using SMTP with IIS

You can set up both IIS and SMTP services via
the Windows control panel. The SMTP service’s role is to accept and
deliver the messages using the server’s configuration. It may
deliver the messages directly, or utilize a smart host to deliver
the message instead. When a smart host is enlisted, all messages
are forwarded to it for delivery.

A little more information is appropriate for
debugging. The SMTP service uses a directory structure to contain
messages prior to delivery with the default directory being
C:\Inetpub\mailroot. It contains numerous subdirectories including
Queue, Drop, and Badmail. If you’re unable to configure your
instance of the SMTP Service for delivery, you can find the message
in an EML file in the Queue subdirectory. The Badmail directory
contains messages that that couldn’t be delivered. Now, let’s take
a look at sending mail messages from your code.

Sending e-mail messages

To compose an e-mail message in your code, you
need to start by creating an instance of the MailMessage class, as
shown in the following C# snippet:

MailMessage msg = new MailMessage();

Be sure to include the System.Web.Mail
namespace in your code:

using System.Web.Mail;

Once the object is instantiated, the various
properties of the MailMessage class are used per your application.
The following lines set the recipient, sender, and subject of the
message:

msg.To = “test@test.com”;
msg.From = “me@test.com”;
msg.Subject = “Test Message”;

The next step is setting our mail server via
the SmtpServer object’s SmtpServer property:

SmtpMail.SmtpServer = “smtp server name or
address”;

The final step is sending the message by
passing our MailMessage object to the SmtpMail object’s Send
method:

SmtpMail.Send(msg);

The previous code used C#. Here’s a more
complete listing via a Web form’s Page_Load event coded in
VB.NET:

Private Sub Page_Load(ByVal sender As
System.Object, ByVal e As
System.EventArgs)
Handles MyBase.Load
Dim msg As MailMessage = New MailMessage()
msg.To = “test@test.com”
msg.From = “me@test.com”
msg.Subject = “Test message”
msg.Body = “Message body”
Try
SmtpMail.SmtpServer = ” smtp server name or address “
SmtpMail.Send(msg)
Catch ex As HttpException
Response.Write(“Error: ” + ex.ToString())
Catch ex As Exception
Response.Write(“Error: ” + ex.ToString())
End Try
End Sub

Notice a try/catch block is used to catch any
exceptions raised during e-mail message composition. The equivalent
C# code follows:

private void Page_Load(object sender,
System.EventArgs e) {
MailMessage msg = new MailMessage();
msg.To = “test@test.com”;
msg.From = “me@test.com”;
msg.Subject = “Test message”;
msg.Body = “Body of the message”;
try {
SmtpMail.SmtpServer = “smtp server name or address”;
SmtpMail.Send(msg);
} catch (HttpException ex) {
Response.Write(“HTTP Error: ” + ex.ToString());
} catch (Exception ex) {
Response.Write(“Error: ” + ex.ToString());
} }

A straightforward approach to e-mail

The .NET platform makes the task of sending
e-mail messages easier. The System.Web.Mail namespace includes
everything necessary to send these messages–that is, except the
actual SMTP server.

You must set up an SMTP server on the
application’s host box, or you must redirect it to the appropriate
address. IIS provides one approach with its SMTP add-on service,
allowing an SMTP server to be set up to handle the messages or to
utilize a smarthost indicating what server will handle the
processing.

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