Aspose.Email  for .NET

eSign EML Formats in C#

Native and high performance EML message electronic signature using server-side Aspose.Email for .NET APIs, without the use of any software like Microsoft or Open Office, Adobe PDF.

How to Digitally Sign EML File Using C#

In order to electronically sign EML file, we’ll use

Aspose.Email for .NET

API which is a feature-rich, powerful and easy to use digital signature API for C# platform. Open


package manager, search for Aspose.Email and install. You may also use the following command from the Package Manager Console.


PM> Install-Package Aspose.Email

Steps for e-Signing EML Files in C#

A basic message digital signature with

Aspose.Email for .NET

APIs can be done with just few lines of code. One can sign email processing documents by adding text, image or draw professional digital signature to the email files as well as save result in MSG and EML formats.

  • Load all the EML files with full path.
  • Set the style of text like font, font size, color etc.
  • Set the Signature text.
  • Save EML file, You will get the document with signature inserted.

System Requirements

Our APIs are supported on all major platforms and Operating Systems. Before executing the code below, please make sure that you have the following prerequisites on your system.

  • Microsoft Windows or a compatible OS with .NET Framework, .NET Core, and Xamarin Platforms
  • Development environment like Microsoft Visual Studio
  • Aspose.Email for .NET DLL referenced in your project - Install from NuGet using the Download button above

e-Sign EML Files - C#

var mail = MapiHelper.GetMapiMessageFromFile(inputFilePath);

var htmlDocument = new Aspose.Html.HTMLDocument(mail.BodyHtml, "");

var element = htmlDocument.CreateElement("Signature");
element.InnerHTML = "Signature Text (Style it with css)";

var folderPath = "directorypath";
var filePath = folderPath + "Merged.html";
var content = System.IO.File.ReadAllText(filePath);
mail.SetBodyContent(content, BodyContentType.Html);

mail.Save(Path.Combine(outputFolderPath, Path.GetFileNameWithoutExtension(inputFilePath) + " Signed.eml"), new EmlSaveOptions(MailMessageSaveType.EmlFormat));  
  • About Aspose.Email for .NET API

    Aspose.Email is a Microsoft Outlook and Thunderbird formats parsing solution. One can easily create, manipulate, convert email and storage formats such as MSG, EMLX, EML and MHT. Handling of email attachments, customization of message headers and implementation of different network protocols like POP3, IMAP & SMTP to send & receive emails is much easier. Its a standalone API and does not require Microsoft Outlook or any other software installation.

    Online EML eSignature Live Demos

    EML What is EML File Format

    EML file format represents email messages saved using Outlook and other relevant applications. Almost all emailing clients support this file format for its compliance with RFC-822 Internet Message Format Standard. Microsoft Outlook is the default software for opening EML message types. EML files can be used for saving to disc as well as sending out to recipients using communication protocols.

    Read More

    Other Supported Files for Electronic Signatures

    Using C#, One can also digitally sign many other formats including.

    MBOX (Electronic Mail Messages)
    MSG (Outlook & Exchange Format)
    OST (Offline Storage Files)
    PST (Outlook Personal Storage Files)