Last reviewed on November 7, 2014   —  1 Comment

This page deals with tools and methods that add encryption, digital signatures, or rights management to individual messages. For tools dealing with securing Microsoft Outlook and Microsoft Exchange data with folder and user permissions, see:

To add encryption and security signatures to Exchange messages on the Internet, you can use either PGP (Pretty Good Privacy) or S/MIME (Secure MIME.) S/MIME support is built into Outlook, starting with Outlook 98. See:

  • OL2000 – Encryption and Message Security Overview
  • OL2002 Encryption and Message Security Overview

Choose Tools | Options | Security. You can add S/MIME support to earlier versions with third-party utilities. CW users note: OL2000 (CW): Rich Text Signed Messages Are Always Sent As HTML. With Outlook 97, you can tell that you’ve received an S/MIME message if it has an attachment with one of these extensions:

.p7s Signed, but not encrypted
.p7c Certificate only, no digital signature or encryption
.p7m Signed and encrypted. Cannot be read except by an S/MIME client

Outlook 2000 SR-1/1a adds support for S/MIME version 3, but most features need to be activated via Windows registry settings.
Public key servers and other services are listed at Secure E-mail Services

Tools and utilities which do not fit any of the above categories are list at Encryption and Message Security Tools

More Information

S/MIME Encryption

Boldon James Email Classifier

Email Classifier labels enforce the organisation's rules on handling and release of email, automatically invoking other technologies such as encryption or rights management.


With MessageLock, you can encrypt your email message and/or file attachments using encryption as strong as AES-256 bit (U.S. Government standard). Or you can send a self-decrypting .exe file that will prompt the recipient for a password before decrypting the message. MessageLock can also collect and manage your passwords, both for sending and receiving encrypted files. This allows MessageLock to encrypt with a single click, and decrypt inbound messages automatically. Also adds integrated Zip Compression. For Outlook 2000 through 2007.

Outlook 2000 128-bit encryption

For Service Release 1 only. Not needed for Windows 2000.


Component of military messaging client based on Outlook supports S/MIME v.3 encryption and signatures.


SecurExchange S/MIME is an Exchange Server component that will automatically digitally sign and/or encrypt mail that meet predefined event or message or attachment content policy conditions. SecurExchange SMIME uses the S/Mime and X.509 Certificate standard and is completely transparent to internal users, thus ensuring compliance to corporate or regulated policies and thereby protecting sensitive information outside of your organization.

Updated 40- or 56-Bit Encryption Provider for Outlook 2000

For Service Release 1 only. Not needed for Windows 2000.

PGP Encryption


cGeep Pro has been designed to automate and simplify encryption actions. Messages are decrypted automatically and attachments are decrypted in one click within Outlook. You are prompted only once for your decryption passphrase during each Windows session, it won’t be requested again for any file and email decryption. cGeep Pro is fully OpenPGP compliant.

PGP Desktop Email

"Pretty Good Privacy" encryption, available in both free and commercial versions. See: OAER Outlook Stops Responding and You Receive an Error That References the Pgpexch.dll File


Shell for PGP security that works with Microsoft Outlook, as well as Exchange. Download PGPCLK35.ZIP

More Information


  1. Martin Leo says

    Here is the simple tool that can be used in Outlook for sending and recieving encrypted and secured e-mails. The tool name is PDF Postman for Outlook. Try it now.

Leave a Reply

Please post long or more complicated questions at OutlookForums by

If the Post Comment button disappears, press your Tab key.