An Outlook Add-In that Prevents ‘Reply All’

Gavin Smyth at Microsoft Research, Cambridge, UK, has created a neat utility for Microsoft Outlook that prevents people from replying to all the recipients of a message or forwarding it. The add-in uses a facility built into Outlook and Exchange that is more lightweight than information-rights management but is not exposed as a feature in the existing UI.

Interestingly, the email recipient does not need to have this add-in installed to have Reply All disabled. The application uses the flags that are handled by Outlook and Exchange, as long as the sender and recipient are on the same Exchange Server. This lightweight utility is designed for accidental replies or forwarding, and is not a robust security solution. The recipient could of course, use the add-in to re-enable Reply All. If you are looking for security, you’ll have to go with IRM.

The add-in also includes a couple of other features to check for common email errors. It warns you if you send an email with a blank subject line. Although this feature is built into Outlook 2010, Outlook 2007 users would like it. It also includes a detector for missing attachments when you send an email. Apart from looking for keywords like attached’ or attachment’ in the body of the email, the add-in has another list intended to be contexts in which the keywords should be ignored (such as legalese in an email signature). The add-in also attempts to distinguish between embedded images and other attachments so an email signature with an image shouldn’t trick the tool into thinking an attachment is already present.

The setup is just 0.63 MB in size and the application works well with Outlook 2007 and 2010. When you launch setup.exe to install, the following components are also installed, if they are not already present, before the  NoReplyAll add-in is installed:

  • Windows Installer 3.1
  • Microsoft.NET Framework 3.5 SP1
  • Microsoft Visual Studio 2010 Tools for Office Runtime


Published by

Abhishek Baxi

Abhishek Baxi is an independent technology columnist for several international publications and a digital consultant. He speaks incessantly on Twitter (@baxiabhishek) and dons the role of Editor-in-Chief here at Techie Buzz.