"The message could not be sent securely" appears when sending an encrypted email

Solution ID Last Updated
1056951 May. 19, 2014 1:35 AM (PST)

Product / Version Platform
Encryption for Email - 5.7, 5.8, 5.9;
Windows - 2000 Advanced Server, 2000 Datacenter Server, 2000 Professional, 2000 Server, 2000 Small Business Server, 2003 Compute Cluster Server, 2003 Datacenter Server, 2003 Datacenter Server Edition 64-bit, 2003 Enterprise Server, 2003 Home Server, 2003 Small Business Server, 2003 Standard Server Edition, 2003 Standard Server Edition 64-bit, 2003 Storage Server, 2003 Web Server Edition, 2008 Datacenter Server, 2008 Datacenter Server Edition 64-bit, 2008 Enterprise Server, 2008 Enterprise Server Edition 64-bit, 2008 Essential Business Server, 2008 Small Business Server, 2008 Standard Server Edition, 2008 Standard Server Edition 64-bit, 2008 Storage Server, 2008 Web Server Edition, 2008 Web Server Edition 64-bit, 7 32-bit, 7 64-bit, Mobile 5 Pocket PC, Mobile 5 Pocket PC Phone Edition, Mobile 5 Smartphone, Mobile 6 Classic, Mobile 6 Professional, Mobile 6 Standard, NT 4.0 Server, NT 4.0 Workstation, Vista 32-bit, Vista 64-bit, XP Home, XP Professional, XP Professional 64-bit

Problem Description

When you try to send an encrypted email using Trend Micro Encryption for Email (TMEE), the following error message appears:
The message could not be sent securely


The error occurs when the following plug-ins are disabled or not installed in Outlook:
  • Private Post Attachment Handler
  • Private Post v4
To resolve the issue:
  1. On Outlook 2007, go to Tools > Trust Center > Add-ins.
  2. Select Exchange Client Extensions from the Manage dropdown list, and then click Go.
    Exchange Client Extensions
  3. Make sure that the following options in the Add-In Manager window are enabled:
    • Private Post Attachment Handler
    • Private Post v4
    Add-In Manager window
  4. Click OK.
  5. Restart Outlook.

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