Widgets for Microsoft Exchange
Rich Text Sentry

Rich Text Sentry

Exchange makes it very easy to send a rich text message to a recipient running a client other than Exchange. That recipient will see a huge, unreadable chunk of encoded binary data. If that recipient happens to be an Internet mailing list, five thousand users will each receive that chunk.

Rich Text Sentry helps guard against such embarrassing accidents.

Requirements and contraindications

As of version 0.4.0, Internet Idioms subsumes all of the functionality of Rich Text Sentry. Hence you need not install Rich Text Sentry if you already run Internet Idioms. See the Check outgoing messages for accidental rich text checkbox.

To use Rich Text Sentry, you must be using a message service that addresses its messages with the SMTP address type, such as Microsoft Internet Mail and Netscape Internet Mail.

MSN users need not load Rich Text Sentry, since MSN already filters all rich text from messages that leave it.

Rich Text Sentry will not work with MS Office 95 WordMail, since the WordMail forms don't support client extensibility. For the same reason, it will not work with the simplified send note included in the Windows 95 Messaging Update.


Download rtfguard.zip (available in both Intel and Alpha flavors) from this Web page, and unzip it. Copy the DLL rtfguard.dll into your system directory (\windows\system on Windows 95, \windows\system32 on Windows NT). Check your system directory for the file msvcrt40.dll on Alpha, or msvcrt.dll version 4.20.6201 on Intel; if you lack this, see the runtime installation instructions. Finally, merge the contents of the file rtfguard.reg into the registry, either by double-clicking its icon in the Windows Explorer or by selecting Merge from its right-mouse-button context menu.


Exit and log out of Exchange. Fire up regedit, open the key


and delete the "Rich Text Sentry" tag and its value. Delete the file rtfguard.dll from your system directory.


The Rich Text Sentry guards against the common mistake of sending Exchange-format rich text messages to Internet recipients not using Microsoft Exchange.

Once installed, Rich Text Sentry watches every outgoing message for Internet recipients with the Send to this recipient in Microsoft rich text format flag set. When it finds a message with such, it warns the user, who may send the message as it is, stop sending the message, or else have Rich Text Sentry eliminate the rich text setting.

A user can circumvent this check by selecting the recipient from the Address Book. Rich Text Sentry assumes that any recipient selected from an Address Book bears an intentionally set (or reset) rich text flag.

Known shortcomings and bugs in this release

Rich Text Sentry cannot tell that you're responding to a message that contained rich text in the first place.

When replying to an Internet mail message, Rich Text Sentry cannot tell that you have an entry for the sender in your PAB, since Exchange is not using that entry in your reply note. (Exchange instead is using a one-off recipient that it has generated from the address information in the original note. This problem is not unique to Internet mail; rather, it results from the mail system not using a central directory.) As a result, you may have an entry in your PAB specifying that this particular correspondent accepts rich text mail, yet Rich Text Sentry will still warn you about sending rich text. You must manually replace the recipient entries in the note's To and Cc fields with entries that you select from the Address Book in order for Rich Text Sentry to honor the rich text setting in those entries.

There is no way to make this extension check Internet-destined mail sent through a Microsoft Mail gateway.

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Last modified: 13 August 1998

Ben Goetter (contact information)

Copyright 1996-1998 Ben Goetter. All rights reserved.