OpenMSG Viewer Pro
Evaluation Build
Try the full Enterprise build in your own sandbox — zero telemetry, Group Policy control, hardened attachment handling, and a Windows Event Log audit trail.
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Built for Managed Environments
Silent, centrally managed MSIX deployment
The Enterprise build ships as a standalone MSIX package outside the Microsoft Store. Deploy it through Intune, SCCM, or a startup script — users see no installer prompts and no configuration screens.
Silent MSIX deployment
Deploy the same package through Intune, SCCM, or a startup script — no user interaction required.
EULA and privacy pre-accepted
Suppress first-launch prompts machine-wide with two registry values.
Standalone package
Distributed outside the Microsoft Store as a code-signed MSIX, with no Store dependency for managed devices.
No licence servers
Honour-based licensing with no DRM keys, no agents, and nothing to maintain.
Pre-accept on first logon
# Run once as Administrator
New-EventLog -LogName Application -Source "OpenMSG"
$path = "HKLM:\SOFTWARE\OpenMSG"
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name "AcceptEula" -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name "AcceptPrivacyPolicy" -Value 1 -Type DWord
Central Policy Control
Group Policy and the registry — nothing else
Attachment rules, rendering behaviour, appearance, and printing are all configurable machine-wide through Group Policy or the registry. Policy values take precedence, and users cannot override them.
Group Policy first
Values in HKLM\SOFTWARE\Policies\OpenMSG take precedence over all other configuration.
Attachment rules
Allowed extensions, unsafe-attachment blocking, file and attachment size limits, and attachment count caps.
Rendering controls
Control JavaScript in emails, external content loading, mailto: and external links, and the AppContainer sandbox.
Appearance and printing
Lock the theme, hide user controls, disable printing, and replace the title bar text for white-label deployments.
Enforce machine-wide policy
$path = "HKLM:\SOFTWARE\Policies\OpenMSG"
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name "ForceTheme" -Value 2 -Type DWord
Set-ItemProperty -Path $path -Name "HideThemeToggle" -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name "BlockUnsafeAttachments" -Value 1 -Type DWord
Hardened by Default
Safe defaults for untrusted content
Emails are untrusted by nature. The Enterprise build sanitises message HTML before rendering, blocks external content by default, and isolates parsing from the rest of the system.
Sanitised before display
JavaScript event handlers, javascript: links, and auto-redirects are stripped from email HTML.
External content blocked
A strict content policy prevents images and assets loading from third-party servers unless your policy allows it.
Sandboxed parsing
Parsing runs in an isolated AppContainer, separate from the rest of the system.
Disguised files blocked
Magic-bytes verification, executable-signature checks, and Unicode RTLO protection stop spoofed attachments.
before rendering
<img src=banner.png onerror=track()>
<a href=javascript:open()>
Sanitised before display
- JavaScript stripped from email HTML
- External images and assets blocked by default
- Parsing isolated in an AppContainer sandbox
- Disguised executables blocked before opening
Nothing Leaves Your Network
Zero telemetry, full local audit trail
The Enterprise build sends no analytics and no crash reports, so no end-user data reaches us. Audit logging stays on your infrastructure, in the Windows Event Log.
Zero telemetry
Analytics, crash reporting, rating prompts, licensing banners, and in-app messages are permanently disabled.
Event Log audit trail
File opens, attachment events, and link handling are recorded under the OpenMSG source in the Application log.
No end-user PII
Nothing about your users or their email reaches us.
Auditing under your control
Register the event source once per device, or disable the audit trail entirely with policy.
0
Analytics events transmitted
0
Crash reports sent
New-EventLog -LogName Application -Source "OpenMSG"
Audit trail for file opens, attachment events, and link handling — readable in Event Viewer.
Tailor the Interface
Your standards, not your users' preferences
Theme, window behaviour, printing, and branding are all policy-controlled. Lock the interface down where it matters, or give users flexibility where it doesn't.
Lock the theme
Force light or dark mode at launch, or hide the theme toggle from the toolbar entirely.
Hide user controls
Remove drag-and-drop, attachment saving, and printing where review workflows require it.
White-label the title bar
Replace the window title with your organisation's text via AppTitleOverlay.
Print branding suppressed
Print branding and in-app prompts are force-disabled in the Enterprise build — no configuration needed.
Comparison
What the Enterprise build adds
The same fast MSG viewer — with the deployment, policy, and audit controls managed environments need.
| Feature | Consumer (Store) | Enterprise |
|---|---|---|
| Telemetry & in-app prompts | Pseudonymous analytics, opt-out | None — permanently disabled |
| Central configuration | Not supported | Group Policy + registry |
| Attachment controls | Standard safe list | Allowlist, blocking, size limits |
| Audit trail | Not available | Windows Event Log |
| Deployment | Microsoft Store | MSIX · Intune · SCCM |
| Title bar branding | Fixed | Configurable (white-label) |
| Licensing | Free for personal use | Commercial licence required |
Installation
Installs in under a minute — manually or through your management platform.
Download the MSIX package
Choose x64 for most Windows PCs, or ARM64 for Windows on ARM hardware.
Install the package
Double-click the .msix and click Install. Deploy silently via Intune or SCCM using the same file.
Launch and open a .msg file
Launch OpenMSG from the Start menu, or double-click any .msg file to open it.
Apply your policy (optional)
Set Group Policy or registry values before rollout — attachment rules, theme lock, audit logging, and more.
Evaluation build terms
- The evaluation build displays a prominent evaluation watermark and is intended for internal, isolated sandbox evaluation only.
- It must not be deployed into a production Standard Operating Environment. If you need a build without the watermark, purchase a commercial licence.
- Telemetry, crash reporting, and in-app prompts are permanently disabled in this build.
When your evaluation is complete, remove the application:
Need more time? Contact [email protected] for extended evaluation access or deployment assistance.
Documentation
Full IT and Enterprise configuration reference: registry values, Group Policy deployment, attachment security, and privacy controls.
Read the documentation →Need help?
Questions about deployment, policy configuration, or volume licensing? We can help directly.
[email protected]Ready to License?
Volume licensing with no servers to manage, no watermark, and updates included. Plans from 50 users to unlimited site licences.
Ready to evaluate?
Download the package for your architecture, then follow the steps above.