https://support.microsoft.com/zh-tw/help/310262/how-to-use-the-microsoft-outlook-object-library-to-send-an-html-formatted-message-by-using-visual-c
using System;
using System.Reflection; // to use Missing.Value
// TO DO: If you use the Microsoft Outlook 11.0 Object Library, uncomment the following line.
// using Outlook = Microsoft.Office.Interop.Outlook;
namespace SendHTMLMail
{
public class Class1
{
public static int Main(string[] args)
{
try
{
// Create the Outlook application.
Outlook.Application oApp = new Outlook.Application();
// Get the NameSpace and Logon information.
Outlook.NameSpace oNS = oApp.GetNamespace("mapi");
// Log on by using a dialog box to choose the profile.
oNS.Logon(Missing.Value, Missing.Value, true, true);
// Alternate logon method that uses a specific profile.
// TODO: If you use this logon method,
// change the profile name to an appropriate value.
//oNS.Logon("YourValidProfile", Missing.Value, false, true);
// Create a new mail item.
Outlook.MailItem oMsg = (Outlook.MailItem)oApp.CreateItem(Outlook.OlItemType.olMailItem);
// Set the subject.
oMsg.Subject = "Send Using OOM in C#";
// Set HTMLBody.
String sHtml;
sHtml = "<HTML>\n" +
"<HEAD>\n" +
"<TITLE>Sample GIF</TITLE>\n" +
"</HEAD>\n" +
"<BODY><P>\n" +
"<h1><Font Color=Green>Inline graphics</Font></h1></P>\n" +
"</BODY>\n" +
"</HTML>";
oMsg.HTMLBody = sHtml;
// Add a recipient.
Outlook.Recipients oRecips = (Outlook.Recipients)oMsg.Recipients;
// TODO: Change the recipient in the next line if necessary.
Outlook.Recipient oRecip = (Outlook.Recipient)oRecips.Add("email address");
oRecip.Resolve();
// Send.
oMsg.Send();
// Log off.
oNS.Logoff();
// Clean up.
oRecip = null;
oRecips = null;
oMsg = null;
oNS = null;
oApp = null;
}
// Simple error handling.
catch (Exception e)
{
Console.WriteLine("{0} Exception caught.", e);
}
// Default return value.
return 0;
}
}
}