Email signature shows as invalid in Outlook.

Products

• Symantec Products

Issue/Introduction

The recipient of an email signed with a certificate issued through Symantec MPKI shows as invalid.
 

There may be a message showing that the signature is invalid, or that the contents of the message may have been altered.

Cause

Often, emails will be scanned and filtered for content by security devices.  In some cases, links will be removed, or changed to redirect through a proxy.  This invalidates the signature.

Resolution

Test sending plain text email, or an HTML email with no hyperlinks.  Graphics are ok.  The signature should now show as valid.