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A portable library in C# and Java for parsing and generating Internet mail messages.

Note that sending and receiving email messages is outside the scope of this library; however, an application that sends and/or receives such messages can use this library to help interpret those messages.

See the Java API documentation.

See the C# (.NET) API documentation.

Starting with version 0.6.1, the C# implementation is available in the NuGet Package Gallery under the name PeterO.MailLib. To install this library as a NuGet package, enter Install-Package PeterO.MailLib in the NuGet Package Manager Console.

Starting with version 0.6.1, the Java implementation is available as an artifact in the Central Repository. To add this library to a Maven project, add the following to the dependencies section in your pom.xml file:

<dependency>
  <groupId>com.upokecenter</groupId>
  <artifactId>maillib</artifactId>
  <version>0.15.0</version>
</dependency>

In other Java-based environments, the library can be referred to by its group ID (com.upokecenter), artifact ID (maillib), and version, as given above.

Source code is available in the project page.

An example of reading an email message from a file:

// Create a file stream from the email message file
using(var file = new System.IO.FileStream("email.eml",System.IO.FileMode.Read)){
  // Read the email message
  var message = new Message(file);
  // Output each address in the From header
  foreach(var addr in message.FromAddresses){
     Console.WriteLine("From: "+addr);
  }
  // Output each address in the To header
  foreach(var addr in message.ToAddresses){
     Console.WriteLine("To: "+addr);
  }
  // Output the message's text
  Console.WriteLine(message.BodyString);
}

Version 0.15.0:

• Email message Date/Time validity was restricted slightly
• DataUtilities moved to a separate library
• GetBodyString and GetFormattedBodyString changed behavior and functionality
• BodyString property is deprecated
• GetAttachments method added to Message class
• NamedAddress received new string preparation methods
• Update media types

Version 0.14.0:

• Message class can now convert Markdown to HTML, with new method SetTextAndMarkdown
• Unicode data updated to latest version of Unicode
• Date headers in generated messages (Generate()) are in global time
• DataUrls class is now called DataUris; DataUrls is now deprecated.
• Changes in algorithm used by ContentDisposition.MakeFilename
• Add Message.ExtractHeaderField method
• Deprecated IsText and IsMultipart in MediaTypeBuilder
• Changed ParseDateString and GenerateDateString to allow only years 1900 or greater and to fix bugs.
• Bug fixes

Version 0.13.1:

• Java version only: Make Java version depend on Encoding library 0.5.0.

Version 0.13.0:

• The code for parsing and generating message headers and bodies was again rewritten in many places to improve robustness and conformance with RFCs that define the message format and MIME. For instance, parsed messages with an unknown character encoding have their ContentType property set to "application/octet-stream". (The original Content-Type header value is still available.)
• Added methods to parse and generate Data URIs.
• Added methods to parse and generate Mailto URIs.
• Added ClearHeaders method to Message class.
• Added public APIs to handle language tags.
• Changed behavior of MakeFilename in a corner case.
• Added ProtocolStrings class for checking protocol strings.
• Added public APIs to process and generate multiple-language messages (multipart/multilingual).
• Deprecated ToAddresses, FromAddresses, CcAddresses, and BccAddresses properties in Message.
• Added convenience methods in Message class for creating attachments and inline body parts.
• Updated Encoding library reference to 0.5.0.
• Add several methods to DataUtilities class
• Bug fixes

Version 0.12.0:

• The internal code for parsing and generating message headers was extensively refactored. Much of the refactoring improves conformance with RFCs that define the message format and MIME.
• As a result of the refactoring, the message generation can better ensure, when possible, that each line of a generated message is no more than 78 characters long, as recommended by those RFCs.
• Many bugs were fixed, including those relating to downgrading header fields containing non-ASCII characters to ASCII in the Generate method. Another bug involves an infinite decoding loop involving certain Content-Type and Content-Disposition strings.
• One additional deviation to RFC 2047 (encoded words) is noted in the documentation for the Message class. I think the deviation shows a weakness in that RFC.
• At least three methods added to ContentDisposition class, including ToSingleLineString.
• ToSingleLineString method added to MediaType class.
• GenerateBytes method added to Message class.
• Added MailDateTime class.
• MakeFilename class in ContentDisposition is now idempotent and shows better. performance in some common cases of file names.

Version 0.11.0:

• Corrected the documentation for MediaType's and ContentDisposition's Parameters properties
• Added DisplayName property in NamedAddress class
• More robust ContentDisposition.MakeFilename method
• Update Unicode data
• Converted to .NET Standard
• Updated Encoding library used
• Supported parsing several new header fields
• Bug fixes

See History.md for release notes for older versions.

Written in 2013-2018 by Peter O.

Any copyright to this work is released to the Public Domain. In case this is not possible, this work is also licensed under Creative Commons Zero (CC0): https://creativecommons.org/publicdomain/zero/1.0/ (For exceptions, see LICENSE.md.)