LiquidFiles Documentation
LiquidFiles Documentation

LiquidFiles Outlook Plugin


The Outlook plugin will enable you to send files from Microsoft Outlook 2013-2019. Microsoft Outlook for Windows coming with Office 365 subscription is also supported.

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No support for Outlook 2010

Microsoft discontinues Outlook 2010 on 10 October 2020. Therefore, our Outlook plugin 3.0 is not built to support Outlook 2010. If you still use Outlook 2010, please use the plugin version 2.0 or contact us for more information.

LiquidFiles Windows Agent required

Unlike previous versions of LiquidFiles Outlook plugin, this version requires its Windows Agent to be run. This is because the communications between the server and the client are only handled by the Windows Agent. The Windows Agent is included into the Outlook Plugin setup, and it is launched automatically by the plugin.


  • LiquidFiles virtual appliance 3.3.0 or later.
  • Windows Vista or later
  • .NET v4.5 or higher
  • Microsoft Outlook 2013-2019


Outlook plugin will pop up a window asking credentials on first attempt to secure-attach file.

How to select proper mode to install:

  • The setup package can be installed per-user or per-machine (for all users on the machine). We recommend installing it per-machine, including installations on personal non-shared devices such as laptops, unless you have a good reason to install it per-user.
  • Typical scenarios when you would want to install it per-user (for specific user only) include
    • Compatibility issues or security policies preventing installation of the plugin for all users.
    • Selectively controlling which users have access to the plugin on shared computer or terminal server.
    • Allowing user to enable or disable the plugin (enabling the plugin installed for all users at the machine requires Administrative permissions).
  • If you install by downloading the file to the computer and launching it through Windows/Explorer/Shell command prompt, please use EXE version of setup as it will ask for elevated permissions if necessary.
  • If you push setup by GPO, please use MSI. IMPORTANT: do not launch MSI to install Admin version from command prompt, it may result in lack of elevated permissions and therefore plugin will not install properly. Use EXE file instead.


You should run normal installation (launching MSI or EXE file).

You can deploy registry policies by specifying /qn REGKEYSCRIPT parameter to MSI, passing semicolon-separated key/value pairs to command line, such as:

msiexec /i liquidfiles.msi /qn REGKEYSCRIPT="AutoSignInServiceUrl=;BaseUrl="

Using proxy server

By default, both LiquidFiles Outlook Plugin and LiquidFiles Windows Agent use .NET's default proxy, which is what IE uses. So basically as long as you can reach LiquidFiles server with IE, Windows components should work, too. However there`s a problem with authentication. By default, .NET does not use Windows authentication for proxy servers.

To enable that for all .NET applications (not just for LiquidFiles), you need to change machine.config under both

  • C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config
  • C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config

Add or modify <> section. If it does not exist, insert it at the end of config file but before closing </configuration> xml tag:

<defaultProxy useDefaultCredentials="true"/>

It is also possible to specify non-default credentials, but that would require non-trivial steps:

If you do not want to apply this change to all .NET applications, you need to change or create config files for the individual executable files:

  • LiquidFiles.Windows.AgentV3.exe,
  • LiquidFilesCLI.Windows.exe (or older LiquidFilesCLI.exe)

For each of those files, locate appropriate .exe.config file (create it if it does not exist) and insert/update the <> configuration setting as above. If config does not exist, use this template for default config file:

<defaultProxy useDefaultCredentials="true"/>

It is also possible to read non-default configuration from a config file, by specifying path to that file by registry policy ProxyConfigFilePath. However the recommended way to handle this situation is to modify LiquidFiles.Windows.AgentV3.exe.config (and/or configuration files of CLI applications) and make sure that connections are made through LiquidFilesWindowsAgent, or to tweak machine.config file. As of today, there's no official support with .NET for reading default proxy configuration from non-default configuration files, and there's no support to turn on default authentication at runtime either.

Therefore, the best solution would be to either tweak machine.config or change individual config files.

Limited support for Single sign-on (SSO)

At this moment, single sign-on through browser interface is not supported. You can configure LiquidFiles Authentication Proxy to provide seamless, automatic and silent authentication of Windows Agent and Outlook plugin in LiquidFiles. LiquidFiles Authentication Proxy is Microsoft IIS application and needs to be run using Integrated Windows Authentication. Please see the Windows Auth Proxy Documenation for more informationm.

Silent install

msiexec /q /i LiquidFiles_OutlookPluginV3.0.7.msi /l* c:\temp\Liquidinstall.log

Known Issues

  1. Outlook Meetings ribbon is not currently supported yet.
  2. Command-line metadata cleansers are not currently supported yet.
  3. LiquidFiles does not intercept "Send to ... Mail recipient" command from Windows Explorer (and with similar APIs). There is limited support for this scenario. LiquidFiles plugin will eventually process attachment when it has command over Outlook window.
    However, if you attempt this command on a very large file, MAPI policies will prevent file from being sent before Outlook Plugin has a chance to intercept the action. So the only way to allow sending very large files through LiquidFiles is to adjust Exchange policies and allow very large files to be attached in Outlook.
  4. The "Send to" command has been known to crash Outlook in certain Citrix environments when used to start Outlook. (it would not crash if Outlook is already running).

Problems on/after install?

Depending on version and permissions of the file system, the following files can be found under `%temp%\LiquidFiles*` folder, or under `%localappdata%\liquidfiles\logs` folder. Please check timestamps of the log files and look in all possible locations.

Filename Default location Log description
adxregistrator.log %temp%\LiquidFiles* Log of install/uninstall process (add-in only). Can be shared between several add-ins.
adxloader.log %temp%\LiquidFiles* Log of add-in loading process. Can be shared between several add-ins.
LiquidFiles.OutlookPluginV3.log %LocalAppData%\LiquidFiles\Logs Log file of LiquidFiles Outlook plug-in
LiquidFiles.Windows.AgentV3.log %LocalAppData%\LiquidFiles\Logs Log file of LiquidFiles Windows agent

If in doubt, please zip contents of that folder and send us the logs through filing support ticket.

Re-enabling the plugin

On occasion, Outlook or an anti-spyware application may disable a plugin. Here's procedure to troubleshoot

1. Check that the Auto-start is still enabled for the plugin

Outlook will auto-load plugins when when registry key LoadBehavior=3 is set for that specific plugin.

Check the following locations

Version Registry key
per-user install HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\LiquidFiles_OutlookPluginV3.AddinModule
per-machine install, 32-bit Outlook on 64-bit OS HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\Outlook\Addins\LiquidFiles_OutlookPluginV3.AddinModule
per-machine install, Outlook has same bitness as OS HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins\LiquidFiles_OutlookPluginV3.AddinModule

2. Check/Update Resiliency settings

Check the following registry key:

  • Outlook 2019: HKEY_CURRENT_USER\Software\Microsoft\Office\17.0\Outlook\Resiliency\
  • Outlook 2016: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Resiliency\
  • Outlook 2013: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Resiliency\
  • Outlook 2010: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Resiliency\

If Outlook has blacklisted the plugin, you might just delete everything under CrashingAddinList and DisableItems nodes under that registry keys (or use Outlook's "Disabled Items" dialog to re-enable plugin individually).

Alternatively, you can add plugin's ID to under DoNotDisableAddinList with value=1

Plugin ID is LiquidFiles_OutlookPluginV3.AddinModule