Introduction

OutlookHeaders is a simple Microsoft Outlook add-in for Windows that allows to adjust your outbound email messages and http headers. Such may be required for your SMTP service, or for other internal needs in your organization.

Installation

First, obviously make sure that Microsoft Outlook (of supported version) is installed and configured on the workstation(s) that you'll be installing OutlookHeaders add-in. Then your further installation steps will depend on the environment that you're going to use it in:

• Single Workstation (Fresh install): [Most common use.] Download and run the installer (bundle). Make sure to close Microsoft Outlook before installation. When installation is complete restart Outlook.
• Single Workstation (Pre-configured install): Download a non-bundled installer for non-interactive installation. (You can either pick a per-user installer, or an installer for all-users on your workstation.) Then to install this add-in with pre-configured settings, do the following:
  • Create a configuration file, with .ohxml extension, by using another instance of this add-in. You can make a configuration file by going to File -> Export to File, that will save all existing settings in the add-in into .ohxml file:
    

    

  • To specify the .ohxml file to be used during installation of the add-in on new workstation(s), use one of the following methods:
    • Rename configuration .ohxml file into ImportData.ohxml and place it into the same directory as the installation OutlookHeadersInstaller.msi file. If so, the installer will automatically use that configuration file during installation.
    • Use the IMPORTDATA= command line parameter (case sensitive) for the msiexec command. Example:

      msiexec.exe /q /i OutlookHeadersInstaller.msi IMPORTDATA="path-to\export.ohxml"

      This command will quietly (/q) install (/i) OutlookHeaders add-in with the settings pre-configured from the specified export.ohxml file.

  • You can also specify additional settings for this add-in during installation. For that use one of the following methods:
    • Use the STARTUPFLAGS= command line parameter (case sensitive) to specify the following initial settings for this add-in. Specify any combination of the following flags, or none, by adding their values as integers:
      • 1 = to start this add-in disabled. (By default this add-in is enabled after installation.)
      • 2 = to enable logging of debugging information into diagnostic event log when emails are sent out from Outlook. (Used for troubleshooting purposes only.) All logs will remain on the workstation where the add-in is running. (By default this option is disabled.)

      Example:

      msiexec.exe /i OutlookHeadersInstaller.msi STARTUPFLAGS=1

      Will install this add-in initially disabled.

    • Alternatively, you can place the StartupFlags.txt file into the same directory as the installation OutlookHeadersInstaller.msi file. If so, the installer will automatically read it during installation. That file must contain only a text representation of a decimal integer for the value of startup flags, similar to the ones described above for the STARTUPFLAGS= command line parameter.
  Note that this type of installation is not supported by the installer (bundle).
  To be able to install this add-in from a non-bundled installer, the following pre-requisites must be already installed on the target workstation: .NET Framework v 3.5, and Visual Studio 2010 Tools for Office Runtime environment. We could not include them into a non-bundled non-interactive installer due to Microsoft licensing requirements.
• Multiple Workstations (Active Directory): To install this add-in on multiple workstations, download and use any of the non-bundled installers for your GPO deployment. We recommend using the installer (for all-users) for per-machine installation, or the installer (per-user) for user-specific installation.

  To enable a pre-configured installation, place the OutlookHeadersInstaller.msi file into a shared folder where it can be read by all workstations that this add-in is being installed on. After that you can place the configuration .ohxml file into the same shared folder along with the installer. Make sure to rename that file into ImportData.ohxml, as was described above. Additionally you can also place into the same folder the StartupFlags.txt file with other settings, as was described above.

  Note that this type of installation is not supported by the installer (bundle).
  To be able to install this add-in from a non-bundled installer, the following pre-requisites must be already installed on the target workstations: .NET Framework v 3.5, and Visual Studio 2010 Tools for Office Runtime environment. We could not include them into a non-bundled non-interactive installer due to Microsoft licensing requirements.

Operation

Once installed, you can find the OutlookHeaders add-in menu in the Microsoft Outlook command bar under the "Mail Headers" title:

• Latest Outlook versions, in the Add-ins tab:
  
• Older Outlook versions, in the main menu:
  

• Enabled - when checked will enable features of this add-in that are described below. To disable all features of this add-in, uncheck this menu item. In that case, the add-in will display "Mail Headers (Disabled)" in the Outlook command bar:
  
• Customize Outbound Mail - will open a new window that will allow you to set up features of this add-in.

Customize Outbound Mail

This window provides visual user interface to set up features of this add-in:

The OutlookHeaders add-in provides two basic types of settings:

• <ALL> - that apply globally to all email accounts in Outlook.
• Per-email - that apply only to specific email account.

The account that is currently selected is displayed in the "Account:" drop-down control:

The difference between the <ALL> and per-email account is in the way this add-in applies settings: it first applies <ALL> account settings, and only then it applies per-email account settings, if available.

While a per-email account is selected, all checkbox controls in the window will behave in a three-way mode as such:

• Checked - - the option will be turned on for selected email account.
• Unchecked - - the option will be turned off for selected email account.
• Indetermined - - the option will be inherited from the <ALL> account.

Once selected, the following features are available:

• "Custom headers" list - contains a list of http headers to be applied to the selected email account. Entries that are checked in the list, will be included as http headers when sending emails from this account:

  

  Enties that are higher on the list will be included first. To move entries up and down in the list, select them first (you can Ctrl-click or Shift-click to select multiple entries), then right-click the selection, and pick "Move up" or "Move down" from the pop-up context menu. Additionally, similar commands are available in the Edit option of the main menu on top, or via the Ctrl+Up and Ctrl+Down keyboard shortcuts.

  To add a new http header entry click the "+" button in the bottom-right corner, or select "Add New Header" from the Edit option of the main menu on top, or press Ctrl+N keyboard shortcut. A new window will appear that will let you specify the http header's name and body fields.

  
  Note that not all characters are allowed in the name and body fields of an http header. OutlookHeaders add-in will attempt to warn you if you used an illegal character.

  To modify an existing http header double-click it in the list, or first highlight it in the list and then right-click it and select "Edit" from the pop-up context menu. Additionally, similar command is available in the Edit option of the main menu on top.

  To delete one or more http headers from the list, first highlight them (you can Ctrl-click or Shift-click to select multiple entries) and then press the "-" button in the bottom-right corner, or select "Delete Header(s)" from the Edit option of the main menu on top, or press Ctrl+D keyboard shortcut.

  A warning will be displayed before running this command.

  Note that if per-email account is currently selected, you will not be able to modify or delete entries that were inherited from the <ALL> account. Those entries will be labeled as "ALL" in the first column in the list and will be rendered in gray text. They will always appear on top of the list. To modify those entries, switch to the <ALL> account first.

• Overwrite Mail Client Name - when enabled, will overwrite the name of the application that sends your emails with whatever you type in this field. For a quick access to some predefined email clients, click the "..." button on the right and select a name from the list.

  Information: By default, Outlook puts itself into this field, along with its version. This may not be ideal for security reasons, as anyone receiving your emails will know the type and version of the email client that is used in your organization. Spammers, or attackers can use this information to send targeted attacks againt your specific mail client. By overwriting this field with some unrelated, or even bogus mail client name you will minimize such exposure.

• Suppress initial "Received" header - when enabled, will allow you to suppress the initial received: http header that is provided by Outlook by default. You can specify any text in this field. For a quick access to some predefined entries, click the "..." button on the right and select an entry from the list.

  Additionally, this field supports the following meta-symbols (that must be provided as shown below in case-sensitive form):

  • #DEST_EMAIL_ADDR# - will be replaced with an email address of the recipient.
  • #DATE_UTC# - will be replaced with the current UTC date & time in the following format: DayOfTheWeek, Day Month Year Hr:Min:Sec +0000 (UTC). Example: Sun, 02 Jul 2020 23:09:54 +0000 (UTC).

  Example of using meta-symbols in this field:

  from 8.8.8.8 by auto-mailer for #DEST_EMAIL_ADDR#; #DATE_UTC#

  Information: By default, Outlook will generate the received: http header for you. The main issue with this is that such header will contain the public IP address of the computer where you are sending your emails from. In case of an organization, exposing such public IP may jeopardize security of a particular workstation where the email was sent from, as well as subject it to spamming, spear-phishing, or other targeted attacks.

  Note that there's no guarantee that the "received" header that you provide in this field will be transmitted as such to the recipient of your email.
  IMPORTANT: If you're intending to use this feature to hide your IP address while sending spam or other malicious emails, be advised that your ISP, or SMTP service provider will still see your public IP address.
• Reply / Reply-All / Forward section - allows you to customize the look of your email messages when you click Reply, Reply-All, or Forward buttons in Outlook:
  • Change email format to dropdown list - lets you specify the format of the body of the email message.
    • <Inherit> - to inherit this setting from the <ALL> account.
    • Don't Change - will not apply any changes to the email message body.
    • Plain text - will remove all formatting, pictures and links from the email message body. (This may also prevent your SMTP service from adding a tracking pixel into your email.)
    • HTML - will format email message body as HTML. This will allow inclusion of rich text and graphics into your email, as well as a tracking pixel.
    The format specified in this option will be applied regardless of the format of the original email message that you are replying to, or forwarding.
  • Set CSS Style - when enabled, will allow you to provide a list of CSS selectors to apply to the HTML format of your email message body. You can specify any CSS markup as you would normally include in the inlined <style> tag of an HTML document. For a quick access to some predefined styles, click the "..." button on the right and select an entry from the list.
  • Remove tracking pixel - when enabled, will allow you to remove tracking pixel for the domain name(s) specified in this field, if such is found in the email message when you reply or forward it. To specify multiple domain names separate them with a space. For a quick access to some predefined services, click the "..." button on the right and select an entry from the list.

    This add-in assumes that the tracking pixel was included in the text of an email in the following format:

    <url-to-tracking-pixel>

• Apply button - saves changes in the window into persistent storage.
  To cancel, or discard all changes, click the X (close) button in the top-right corner.

Main Menu

The menu with commands supported by this add-in is located on top of its window:

The following options are available:

• File:
  • Save - saves current changes to persistent storage. You can also do the same by hitting Ctrl+S keyboard shortcut.
  • Import from File - will display a file picker window that will allow you to pick a file to import previously exported configuration settings from.
    WARNING: Importing new data will overwrite your existing settings in the OutlookHeaders add-in.
  • Export to File - will display a file picker window that will allow you to pick a file to save configuration settings from this add-in. Use this command to propagate your pre-configured settings among multiple workstations. (See installation section above.)
  • Exit - will close this window.
    A warning will be displayed if the window contained unsaved data.
• Edit:
  • Edit Header - will display the currently selected http header in the list below for editing. You can also achieve the same by double-clicking the http header entry in the list with the mouse. Only one http header can be edited at a time.
  • Add New Header - will display a window that will allow you to add a new http header to the list below. You can also do the same by pressing Ctrl+N keyboard shortcut.
  • Move Header(s) Up - will move selected http headers up by one position in the list below. Headers that appear higher on the list will be included first. You can also do the same by pressing Ctrl+Up keyboard shortcut.
  • Move Header(s) Down - will move selected http headers down by one position in the list below. Headers that appear higher on the list will be included first. You can also do the same by pressing Ctrl+Down keyboard shortcut.
  • Delete Header(s) - will remove selected http headers from the list below. You can also do the same by pressing Ctrl+D keyboard shortcut.
    A warning will be displayed before running this command.
  • Delete All Headers - will delete all http headers from all accounts in this add-in. Use this option only when completely resetting this add-in!
    A warning will be displayed before running this command.
• Window:
  • Restore Window - will restore the main window of this add-in to the middle of the screen. This command could be handy if the window was restored in a hidden area of the screen after a change in your display resolution. You can also activate this command by pressing Ctrl+Shift+R keyboard shortcut.
  • Reset List Columns - will reset the columns of the http headers list to their predefined widths. This can be handy after resizing the main window.
• Help:
  • Online Help - will display the current version of this document in the online help page.
    Internet connection is required.
  • Check for Updates - will open your web browser and load up our website that will inform you if you need to update your version of this add-in.
    Internet connection is required.
  • Report a Bug - will open your web browser and load up our website that will allow you to submit a bug report to developers of this add-in. Please make sure to type up the adequate description of the bug for our support team.
    Internet connection is required.
  • Open Event Log - will open Windows Event Log that could be used to track issues that you may be experiencing with this add-in. All of its diagnostic messages will be logged under "OutlookHeaders Add-in" source.
  • About this Add-in - will display the window with information and version of this add-in.

    This window will also provide some debugging information and a setting to "Log diagnostic events when mail is sent". Such option is disabled by default to preserve your privacy. If enabled, it will create a local entry in the Windows Event Log with some diagnostic (debugging) information every time this add-in intercepts your email during sending.

    IMPORTANT: This add-in does not send any of the diagnostic information "to the cloud", or off the local workstation that it's running on.

Troubleshooting

In the event you encounter issues while running this add-in, you can check Windows Event Log for the presence of messages logged under the "OutlookHeaders Add-in" source. These log entries will contain technical information about operation of the OutlookHeaders add-in. Any errors logged under that source will indicate an issue.

Additionally, you can enable diagnostic event logging when this add-in processes emails before sending them. For that go to Help -> About this Add-in and put a check in the "Log diagnostic events when mail is sent" box. Then click OK to save.

Uninstallation

To remove OutlookHeaders add-in, first close Microsoft Outlook, then go the Windows Control Panel and uninstall it from the "Program and Features" window. It will be listed under "OutlookHeaders" with its installation type and version following it.

Additionally, if you used a non-bundled installer, you can uninstall this add-in using the original OutlookHeadersInstaller.msi file, issuing the msiexec command. Example:

msiexec.exe /x "path-to\OutlookHeadersInstaller.msi"

If you installed this add-in via a Group Policy Object (or GPO) then remove it via the "Group Policy Management" console on your Active Directory server.

Thank you!

Feel free to send us your bug reports and suggestions for improvement. Even though we can't answer every single email, we listen and appreciate your time writing us!

Support Team
www.dennisbabkin.com