Valid Certificate Required in Outlook 2007

This section describes how to request digital signature and encryption when sending an outgoing email message in MS Office Outlook 2007. An invalid certificate error message shows up if you don't have any personal certificate that matches your email address and is issued from a trusted root CA.

Now let's try to send a test email message with encryption and digital signature.

1. Run Outlook 2007 and click "New" to create a new test email message.

2. Click the Digital Signature icon and the Encrypt icon in the "Options" menu group under the "Message" menu.

3. Click the "Send" button. Outlook displays an error message: "Microsoft Office Outlook cannot sign or encrypt this message because your certificate is not valid." See the picture below:
Outlook 2007 Invalid Certificate Error

Looks like I need good certificate that matches my email address and signed by a trusted root CA to be able to use Outlook S/MIME encryption and digital signature functions.

Last update: 2011.

Table of Contents

 About This Book

 Introduction of PKI (Public Key Infrastructure)

 Introduction of HTTPS (Hypertext Transfer Protocol Secure)

 Using HTTPS with IE (Internet Explorer) 10

 Using HTTPS with Chrome 40

 Using HTTPS with Firefox 35

 Perl Scripts Communicating with HTTPS Servers

 PHP Scripts Communicating with HTTPS Servers

 Java Programs Communicating with HTTPS Servers

 Certificate Stores and Certificate Console

 .NET Programs Communicating with HTTPS Servers - Root CA Offering Free Certificates

 PKI CA Administration - Issuing Certificates

 Digital Signature - Microsoft Word 2007

 Digital Signature - 3

S/MIME and Email Security

 What Is S/MIME?

 Digital Signature Scheme for Email Messages

 A Simple Email Message Example

 Email Messages with Attachments using MIME

 Email Messages with Digital Signatures using S/MIME

 Encrypted Email Messages using S/MIME

 Digital Signature and Encryption in Outlook 2007

 Email Security Settings in Outlook 2007

Valid Certificate Required in Outlook 2007

 Message Security Properties in Outlook 2007

 Firefox Extension - Gmail S/MIME

 PKI (Public Key Infrastructure) Terminology

 Outdated Tutorials


 PDF Printing Version