.NET Core C#
Send HTML Email with Attachments

Demonstrates how to send an HTML email with file attachments.
Chilkat .NET Core C# Downloads

.NET Core C#
bool success = false;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.MailMan mailman = new Chilkat.MailMan();

mailman.SmtpHost = "smtp.my-starttls-mail-server.com";

mailman.SmtpUsername = "MY-SMTP-USERNAME";
mailman.SmtpPassword = "MY-SMTP-PASSWORD";

mailman.StartTLS = true;
mailman.SmtpPort = 587;

// Create a new email object
Chilkat.Email email = new Chilkat.Email();
email.Subject = "Test SMTP API to Send HTML Email with Attachments";
email.From = "Joe Programmer <joe@my-starttls-mail-server.com>";
email.AddTo("Chilkat Support","support@chilkatsoft.com");

// Add a plain-text alternative body, which will likely never be seen.
// (It is shown if the receiving email client is incapable of displaying HTML email.)
email.AddPlainTextAlternativeBody("This is a plain-text alternative body...");

// Our HTML will include an image, so add the related image here.
string contentIdStarfish = email.AddRelatedFile("qa_data/jpg/starfish.jpg");
if (email.LastMethodSuccess != true) {
    Debug.WriteLine(email.LastErrorText);
    return;
}

// The src attribute for the image tag is set to the contentIdStarfish:
Chilkat.StringBuilder sbHtml = new Chilkat.StringBuilder();
sbHtml.Append("<html><body><p>This is an HTML email with an embedded image.</p>");
sbHtml.Append("<p><img src=\"cid:CONTENT_ID_STARFISH\" /></p></body></html>");
int numReplacements = sbHtml.Replace("CONTENT_ID_STARFISH",contentIdStarfish);

email.AddHtmlAlternativeBody(sbHtml.GetAsString());

// Finally, add some attachments to the email.
// Add a file attachment.
success = email.AddFileAttachment2("qa_data/pdf/fishing.pdf","application/pdf");
if (success != true) {
    Debug.WriteLine(email.LastErrorText);
    return;
}

// Add an attachment where the content is contained in a string.
string content = "This is the content of the 2nd attached file.";
email.AddStringAttachment("someText.txt",content);

// Send the HTML email.
success = mailman.SendEmail(email);
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

success = mailman.CloseSmtpConnection();
if (success != true) {
    Debug.WriteLine("Connection to SMTP server not closed cleanly.");
}

Debug.WriteLine("HTML email with attachments sent!");