ContentType.Boundary Property

Definition

Gets or sets the value of the boundary parameter included in the Content-Type header represented by this instance.

C#
public string? Boundary { get; set; }
C#
public string Boundary { get; set; }

Property Value

A String that contains the value associated with the boundary parameter.

Examples

The following code example displays the value of the Boundary property.

C#
public static void CreateMessageWithMultipleViews(string server, string recipients)
{
    // Create a message and set up the recipients.
    MailMessage message = new MailMessage(
        "jane@contoso.com",
        recipients,
        "This email message has multiple views.",
        "This is some plain text.");

    // Construct the alternate body as HTML.
    string body = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\">";
    body += "<HTML><HEAD><META http-equiv=Content-Type content=\"text/html; charset=iso-8859-1\">";
    body += "</HEAD><BODY><DIV><FONT face=Arial color=#ff0000 size=2>this is some HTML text";
    body += "</FONT></DIV></BODY></HTML>";

    ContentType mimeType = new System.Net.Mime.ContentType("text/html");
    // Add the alternate body to the message.

    AlternateView alternate = AlternateView.CreateAlternateViewFromString(body, mimeType);
    message.AlternateViews.Add(alternate);

    // Send the message.
    SmtpClient client = new SmtpClient(server);
    client.Credentials = CredentialCache.DefaultNetworkCredentials;

    try
    {
        client.Send(message);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Exception caught in CreateMessageWithMultipleViews(): {0}",
            ex.ToString());
    }
    // Display the values in the ContentType for the attachment.
    ContentType c = alternate.ContentType;
    Console.WriteLine("Content type");
    Console.WriteLine(c.ToString());
    Console.WriteLine("Boundary {0}", c.Boundary);
    Console.WriteLine("CharSet {0}", c.CharSet);
    Console.WriteLine("MediaType {0}", c.MediaType);
    Console.WriteLine("Name {0}", c.Name);
    Console.WriteLine("Parameters: {0}", c.Parameters.Count);
    foreach (DictionaryEntry d in c.Parameters)
    {
        Console.WriteLine("{0} = {1}", d.Key, d.Value);
    }
    Console.WriteLine();
    alternate.Dispose();
}

Remarks

In the following example of a Content-Type header, the value of the Boundary parameter is "-----boundary---0".

content-type: multipart/mixed; boundary=-----boundary---0

Set this property to null or String.Empty to remove the boundary information from the header.

The syntax of the Content-Type header is described in RFC 2045 Section 5.1. An in-depth discussion of the boundary parameter is contained in RFC 2046 Section 5.1.1. These RFCs are available at https://www.ietf.org.

Applies to

Product Versions
.NET Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1