How to add disclaimer using the IMS Extension DLL

Using the IMS Extension DLL (imsext.dll)

Microsoft's Internet Mail Service (IMS) Extension DLL (imsext.dll) is what is used here. When you're using an Exchange Server 5.5 server, imsext.dll lets you add text to the end (append) or to the beginning (prepend) of your inbound or outbound SMTP mail. Let's see what imsext.dll can do for you and how you install and configure this tool.
It is not saved in the server already, you have to install it...

DLL Installation
To implement any of imsext.dll's functionality, you must first install the DLL and configure the IMS to use it. Copy the DLL from the platform\Exchange\Web directory in the Microsoft BackOffice 4.5 Resource Kit CD-ROM to a directory on your Exchange server. Generally, the \exchsrvr\connect\msexcimc\bin directory is the best place.

Next, you need to register the DLL. To do this, open a command prompt, change to the directory where you saved the DLL, and type

[tt]regsvr32 imsext.dll[/tt]

Now, you need to make the IMS aware of the DLL. The imsext.dll documentation tells you to use the custom routing program field on the IMS Routing tab, which Screen 1 shows, to hook the DLL into the system. Microsoft originally intended this hook to expand the system's ability to smarthost, or accept and reroute mail, for other systems. However, this method causes the IMS to lose some functionality that can help prevent unauthorized relaying.

If you've applied at least SP1, you can use an alternative activation method, in which you add a value to the IMS parameters in the Registry. This activation method lets the system complement instead of replace the existing functionality. When editing the Registry, take all the usual precautions; make sure you have a good backup of the Registry before proceeding.

To complete the DLL installation using this alternative method, use regedt32 to access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\MSExchangeIMC\Parameters Registry key. Select the Parameters key, then create a new string value named NonRoutingExtensionDll. Double-click this value, and set the value data to be the filename and full path to imsext.dll. If you use the path I recommended, the full path is C:\exchsrvr\connect\ msexcimc\bin\imsext.dll.

DLL Configuration
You configure this DLL's functionality by editing the HKEY_LOCAL_MACHINE\SYSTEM\ CurrentControlSet\Services\MSExchangeIMC\Parameters Registry key. Create a new key called Extension below the Parameters branch. For each function you want to activate, you create a value below the Extension key.

Adding Text to Messages
To append text, such as a disclaimer, to all outbound mail, you create a string value called OutboundAppend and set the value of OutboundAppend to contain the text you want to add to the end of your SMTP mail. If you want to add formatting to the text, you must use Rich Text Format (RTF) commands. For RTF codes, see the Microsoft article "WD: Rich Text Format (RTF) Specification 1.5 Appnote (GC0165)" at http://support.microsoft.com/ support/kb/articles/q86/9/99.asp contains a link to GC0165.exe, which contains the full RTF specification.

A backslash (\) signals the start of a formatting string, and for this simple RTF example, a space signals the end. You must include a single-space between the RTF string and the text that it's controlling. For example, if you include the RTF string

[tt]\par\bThis message will self-destruct in 5 seconds\b0[/tt]

and don't include a space between the bold on command (\b) and the word This, the system interprets \bThis as a formatting command. Because \bThis isn't a valid command, the system ignores these characters, and the resulting text is
message will self-destruct in 5 seconds.

If the recipient is designated to receive mail with RTF, the IMS preserves the RTF commands (e.g., bold, underline, italics); otherwise, the IMS converts the message to plaintext and preserves only formats such as tab and new line. To make appended text stand out from the original message, include at least a few blank lines at the top of the appended text. To configure the other appending or prepending options, you just use other Registry values (i.e., OutboundPrepend, InboundAppend, and InboundPrepend). However, don't combine too many options because each one adds processing time to the message handling and too many additions can degrade overall system performance. Also, be aware that added text affects MIME digital signaturesùthe text alters the message after it's signed and, therefore, invalidates the signature.

Be sure to obtain management's approval before you implement any of these changes. If you add disclaimers, run the text past your legal advisers to make sure the message is adequate and appropriate. You're probably implementing these features because you believe that they'll protect the company. However, remember to protect yourself, too; management, not IT, must set company policy, especially with regard to policing user activities.

Jay~

~Keytech