C# - Convert Email to HTML

The following c# codes demonstrate how to convert email to a HTML page and display it using Web browser Control.

After the email was converted to HTML page, you can browse it with web browser. You can get everything in the HTML page such as From, To, Cc, Subject, Date, Attachments and Embedded images.

Installation

Before you can use the following sample codes, you should download the EAGetMail Installer and install it on your machine at first. Full sample projects are included in this installer.

Install from NuGet

You can also install the run-time assembly by NuGet. Run the following command in the NuGet Package Manager Console:

Install-Package EAGetMail

Note

If you install it by NuGet, no sample projects are installed, only .NET assembly is installed.

Add Reference

To use EAGetMail POP3 & IMAP Component in your project, the first step is “Add reference of EAGetMail to your project”. Please create or open your project with Visual Studio, then go to menu -> Project -> Add Reference -> .NET -> Browse..., and select Installation path\Lib\[netversion]\EAGetMail.dll, click Open-> OK, the reference will be added to the project, you can start to use it to retrieve email and parse email in your project.

add reference in c#/vb.net/managed c++/cli

.NET Assembly

Because EAGetMail has separate builds for .Net Framework, please refer to the following table and choose the correct dll.

Separate builds of run-time assembly for .Net Framework 1.1, 2.0, 3.5, 4.0, 4.5, 4.61, .NET Core 2.1 and .Net Compact Framework 2.0, 3.5.

File .NET Framework Version
Lib\net11\EAGetMail.dll Built with .NET Framework 1.1
It requires .NET Framework 1.1, 2.0, 3.5 or later version.
Lib\net20\EAGetMail.dll Built with .NET Framework 2.0
It requires .NET Framework 2.0, 3.5 or later version.
Lib\net35\EAGetMail.dll Built with .NET Framework 3.5
It requires .NET Framework 3.5 or later version.
Lib\net40\EAGetMail.dll Built with .NET Framework 4.0
It requires .NET Framework 4.0 or later version.
Lib\net45\EAGetMail.dll Built with .NET Framework 4.5
It requires .NET Framework 4.5 or later version.
Lib\net461\EAGetMail.dll Built with .NET Framework 4.6.1
It requires .NET Framework 4.6.1 or later version.
Lib\netcoreapp2.1\EAGetMail.dll Built with .NET Core 2.1
It requires .NET Core 2.1 or later version.
Lib\net20-cf\EAGetMail.dll Built with .NET Compact Framework 2.0
It requires .NET Compact Framework 2.0, 3.5 or later version.
Lib\net35-cf\EAGetMail.dll Built with .NET Compact Framework 3.5
It requires .NET Compact Framework 3.5 or later version.

C# - Parse and Convert Email to HTML - Example

The following example codes demonstrate converting email to HTML page. In order to run it correctly, please change email server, user, password, folder, file name value to yours.

Note

To get full sample projects, please download and install EAGetMail on your machine.

using System;
using System.Text.RegularExpressions;
using System.Text;
using System.IO;
using EAGetMail; //add EAGetMail namespace

namespace receiveemail
{
    class Program
    {
        static string _formatHtmlTag(string src)
        {
            src = src.Replace(">", ">");
            src = src.Replace("<", "&lt;");
            return src;
        }

        static string _formatAddresses(MailAddress[] addresses, string prefix)
        {
            if (addresses.Length == 0)
            {
                return "";
            }

            StringBuilder buffer = new StringBuilder();
            buffer.Append(string.Format("<b>{0}:</b> ", prefix));

            for (int i = 0; i < addresses.Length; i++)
            {
                buffer.Append(_formatHtmlTag(addresses[i].ToString()));
                if (i < addresses.Length - 1)
                {
                    buffer.Append("; ");
                }
            }

            buffer.Append("<br>");
            return buffer.ToString();
        }

        // We generate a html + attachment folder for every email, once the html is create,
        // next time we don't need to parse the email again.
        static void _generateHtmlForEmail(string emlFile, string htmlFile,
                            string attachmentFolder)
        {
            // For evaluation usage, please use "TryIt" as the license code, otherwise the
            //"invalid license code" exception will be thrown. However, the object will expire in 1-2 months, then
            //"trial version expired" exception will be thrown.
            Mail mail = new Mail("TryIt");
            mail.Load(emlFile, false);

            if (mail.IsEncrypted)
            {
                try
                {
                    // this email is encrypted, we decrypt it by user default certificate.
                    // you can also use specified certificate like this
                    // oCert = new Certificate();
                    // oCert.Load("c:\\test.pfx", "pfxpassword", Certificate.CertificateKeyLocation.CRYPT_USER_KEYSET)
                    // oMail = oMail.Decrypt( oCert );
                    mail = mail.Decrypt(null);
                }
                catch (Exception ep)
                {
                    Console.WriteLine(ep.Message);
                }
            }

            if (mail.IsSigned)
            {
                try
                {
                    // This email is digital signed.
                    Certificate signerCertificate = mail.VerifySignature();
                    Console.WriteLine("This email contains a valid digital signature.");

                    // You can add the certificate to your certificate storage like this
                    // cert.AddToStore( Certificate.CertificateStoreLocation.CERT_SYSTEM_STORE_CURRENT_USER,
                    //      "addressbook" );
                    // then you can use send the encrypted email back to this sender.
                }
                catch (Exception ep)
                {
                    Console.WriteLine(ep.Message);
                }
            }

            // Decode winmail.dat (Outlook TNEF stream) automatically.
            // also convert RTF body to HTML body automatically.MO
            mail.DecodeTNEF();

            string html = mail.HtmlBody;
            StringBuilder header = new StringBuilder();

            header.Append("<font face=\"Courier New,Arial\" size=2>");
            header.Append("<b>From:</b> " + _formatHtmlTag(mail.From.ToString()) + "<br>");

            header.Append(_formatAddresses(mail.To, "To"));
            header.Append(_formatAddresses(mail.Cc, "Cc"));

            header.Append(string.Format("<b>Subject:</b>{0}<br>\r\n", _formatHtmlTag(mail.Subject)));

            Attachment[] attachments = mail.Attachments;
            if (attachments.Length > 0)
            {
                if (!Directory.Exists(attachmentFolder))
                    Directory.CreateDirectory(attachmentFolder);

                header.Append("<b>Attachments:</b> ");
                for (int i = 0; i < attachments.Length; i++)
                {
                    Attachment attachment = attachments[i];

                    string attachmentName = string.Format("{0}\\{1}", attachmentFolder, attachment.Name);
                    attachment.SaveAs(attachmentName, true);

                    header.Append(string.Format("<a href=\"{0}\" target=\"_blank\">{1}</a> ",
                        attachmentName, attachment.Name));
                    if (attachment.ContentID.Length > 0)
                    {   // Show embedded image.
                        html = html.Replace("cid:" + attachment.ContentID, attachmentName);
                    }
                }
            }

            // Change original meta header encoding to utf-8
            Regex reg = new Regex("(<meta[^>]*charset[ \t]*=[ \t\"]*)([^<> \r\n\"]*)", RegexOptions.Multiline | RegexOptions.IgnoreCase);
            html = reg.Replace(html, "$1utf-8");
            if (!reg.IsMatch(html))
            {
                header.Insert(0, "<meta HTTP-EQUIV=\"Content-Type\" Content=\"text/html; charset=utf-8\">");
            }

            html = header.ToString() + "<hr>" + html;

            using (FileStream stream = new FileStream(htmlFile, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                byte[] buffer = Encoding.UTF8.GetBytes(html);
                stream.Write(buffer, 0, buffer.Length);
                stream.Close();
            }
        }

        static void ConvertMailToHtml(string emlFile)
        {
            try
            {
                int pos = emlFile.LastIndexOf(".");
                string attachmentFolder = emlFile.Substring(0, pos);
                string htmlFile = attachmentFolder + ".htm";

                if (!File.Exists(htmlFile))
                {
                    // We haven't generate the html for this email, generate it now.
                    _generateHtmlForEmail(emlFile, htmlFile,attachmentFolder);
                }

                Console.WriteLine("Please open {0} to browse your email",
                    htmlFile);
            }
            catch (Exception ep)
            {
                Console.WriteLine(ep.Message);
            }
        }


        static void Main(string[] args)
        {
            ConvertMailToHtml("c:\\my folder\\test.eml");
        }
    }
}

Appendix

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