Rebex Secure Mail for .NET

SMTP/SSL, IMAP/SSL, POP3/SSL, S/MIME - sending, receiving and processing emails from .NET applications with mail signing, encryption and signature verification.


  • Send e-mail
  • Connect directly to recipient's SMTP server
  • Binary and 8 bit MIME
  • Chunking and pipelining
  • Many authentication methods
  • Delivery status notifications
  • 100% CDONTS and CDOSYS free
  • SMTP over SSL (secure SMTP)
  • SMTP Features
  • SMTP Tutorial


  • Download messages
  • List messages
  • Retrieve message headers
  • Delete messages
  • Message list with headers
  • POP3 over SSL (secure POP3)
  • POP3 Features
  • POP3 Tutorial


  • Download and upload messages
  • Search messages
  • Manage folders (create/rename/delete)
  • Delete messages
  • Get and set message flags
  • Notification events
  • Multiple-message operations
  • List messages and folders
  • IMAP over SSL (secure IMAP)
  • IMAP Features
  • IMAP Tutorial


  • Load and save MIME (.eml) messages
  • Load and save Outlook (.msg) message
  • Simple high-level interface
  • Advanced low-level interface
  • Easy access to header fields
  • Text and HTML message body
  • Linked resources
  • Attachments
  • Quick send via IIS mail queue
  • S/MIME
  • Encrypt and decrypt messages
  • Sign emails and verify signatures
  • MIME features
  • MIME tutorial
  • S/MIME tutorial

Man this is awesome. This product rocks man. Great price too. Its 2am here, I have been looking for the right stuff for ages, thanks again, I will sleep well that this all works.

J. Dean E.P. Hemopo
more testimonials...

Whenever you need to send mail via SMTP, download it with POP3 or access a remote mailbox using IMAP Rebex Secure Mail for .NET will provide the required infrastructure. It allows you to retrieve, create, load, process, save and send e-mail messages in MIME format using a simple yet powerful interface, with no need to understand the complexities of MIME format. And for advanced users, there is a powerful low-level MIME library as well.

Rebex Secure Mail for .NET also enhances the standard SMTP, POP3 and IMAP protocols by utilizing the well known and widely used TLS and SSL protocol. TLS 1.0 and its predecessor SSL 3.0 provide strong authentication, integrity and confidentiality for you communication. This is achieved by using RSA or DSA public key cryptography to authenticate the server (or even the client) and to negotiate the encryption method and symmetric keys to be usedto encrypt your data.

And there is more - S/MIME. This makes it possible to sign mail messages using an X509 certificate, and validate signed messages to make sure they were really send by the sender and not modified during the transit. Also, message encryption is available.

Major features

  • Easy-to-use with maximum flexibility.
  • Upload and download to or from RAM.
  • TLS/SSL for SMTP, POP3 and IMAP.
  • S/MIME signatures and encryption.
  • Free one-year support.
  • Free one-year upgrades.
  • Load/Save in MIME (.eml) and Outlook (.msg) file formats
  • Tutorials for all components.
  • A large number of samples with full C# and Visual Basic .NET source code and different levels of complexity, from simple console utilities to multithreaded WinForm clients.
  • Royalty free redistribution.

Platform support

  • .NET Framework
    2.0, 3.0, 3.5. 4.0, 4.5 both 32-bit and 64-bit editions on Windows XP or later; Visual Studio 2005, 2008, 2010, 2012, 2013
  • .NET Compact Framework
    2.0, 3.5, 3.9 on Windows Mobile, Windows CE, Pocket PC, PDA and SmartPhones, Windows Embedded Compact 2013; Visual Studio 2005, 2008, 2012
  • Mono
    2.10, 3.x on Linux and Apple's OS X
  • Xamarin.iOS
    Xamarin.iOS 6 and 7 ; Xamarin Studio
  • Xamarin.Android
    Xamarin.Android 4 ; Xamarin Studio

More features

  • 100% managed code.
  • CLS (Common Language Specification) compliant.
  • Stable and thoroughly tested code.
  • IPv6 support.
  • Complete C# source code optionally available.
  • Designed for ease of use from your code.
  • Both synchronous and asynchronous operations in SMTP, POP3 and IMAP classes. Designed according to .NET Framework asynchronous operations design patterns.
  • Events for effortless integration with hosting applications.
  • Communication logging using CommandSent and ResponseRead events.
  • Transfer monitoring with the TransferProgress events.
  • Supports advanced authentication methods such as Digest-MD5, CRAM-MD5 and NTLM.
  • Integrated authentication using NTLM.
  • All common firewalls and Socks4, Socks5 and HTTP CONNECT proxy servers are supported.
  • Suitable for both client and server applications.
  • Extensive stream support - download or save mail to stream, load or send mail from stream.
  • Error handling with .NET exceptions.
  • Supports SMTP, POP3 and IMAP over TLS/SSL standards in both explicit and implicit modes
  • Both server and client certificate authentication possible.
  • TLS/SSL key exchange using RSA, DSA or RSA with ephemeral Diffie-Hellman.
  • TLS/SSL encryption/decryption using DES, Triple DES, RC2, RC4 or AES.
  • Support for the forthcoming TLS 1.1 protocol.
  • Certificate validation is fully customizable - your application can have complete control over what is accepted and what is not.
  • Includes SecureSocket component for general use. Defining all aspects of TLS/SSL handshake is possible.
  • Includes component for X509 certificate management, validation, data signature/verification and encryption/decryption.
  • Message signing, signature validation with S/MIME.
  • Message encryption and decryption with S/MIME.

Supported proxy servers

  • Socks4
  • Socks4a (Socks4 with domain name resolving)
  • Socks5
  • HTTP Connect


WinForms samples

  • MIME Explorer
    Views contents of structured MIME files (mail message, .EML or .MHT file).
  • WinForm Mail Sender Application
    Write an e-mail, add an attachment and send it, either synchronously or in the background, with or without progress bar dialog.
  • WinForms POP3 Client - Mailbox Browser
    Allows you to browse, view and manage mail messages in a remote POP3 mailbox, without actually downloading them. Demonstrates how to connect to POP3 server, download emails, read its content, work with attachments.
  • WinForms IMAP Client - Mailbox Browser
    Allows you to browse, view and manage mail messages in a remote IMAP mailbox, without actually downloading them. Demonstrates how to connect to IMAP server, download emails, read its content, work with attachments.
  • Mail Editor
    Windows forms application for editing e-mail files.

Simple commandline utilities

  • SMTP Mail Sender
    Command line e-mail sending utility. Either accepts the sender, recipient, subject, and body from the command line, or loads the e-mail message from the supplied file. Supports SMTP authentication and displays the list of rejected recipients, if any.
  • Simple SMTP Mail Sender
    Very simple command line mail sending utility. Accepts sender, recipient, subject and body from the command line.
  • Interactive SMTP Mail Sender
    Advanced command line application for sending e-mail. Supports attachments and is able to send either using the specified SMTP server, through IIS pickup directory or directly to the recipients' mail servers determined from DNS MX records.
  • Mail Address Verifier
    A simple command line application that verifies whether the specified e-mail address is valid by attempting to resolve its MX records.
  • POP3 Console Client
    Complete command line POP3 client with full source code!
  • POP3 Downloader
    Retrieves a message list from a POP3 server and downloads the messages into local .EML files.
  • IMAP Console Client
    Complete command line IMAP client with full source code!
  • Extract Attachments
    Extracts and saves all attachments from the specified message. Also validates and decrypts the message if appropriate.
  • Mail Converter
    Console application for converting e-mail files between EML(MIME) and MSG(Outlook) formats.
  • IMAP Downloader
    Retrieves a message list from the specified folder of an IMAP server and downloads the messages into local .EML files.

Xamarin.Android samples

Xamarin.iOS samples

Pocket PC and Windows CE Applications

What next?