Microsoft has done it again; I just discovered today that Microsoft has single-handedly managed to prevent S/MIME encryption from ever being used to send e-mail. While many accountants, lawyers, and other professionals use S/MIME signatures, most of their clients don’t.

But that’s okay. Most sane mail software products allow you to reply to a digitally signed message without signing it youself. Except Microsoft. When you try to reply to a digitally signed message, you get the following error:

You cannot send digitally signed messages because you do not have a digital ID for this account.

At this point you have two options. You can hit Get Digital ID, or Cancel. Cancel is certainly not what you want, so let’s try the first link, which takes you here. Lo and behold, it’s a broken URL. Most users at this point will assume that the e-mail message is simply broken and delete it.

If a client uses Outlook Express, they can reply to your message as they normally would, but first they must go to "Tools" in the File menu and uncheck the "Digitally Sign" option for the reply e-mail. They must do this for every digitally signed message. But I don’t see how any inexperienced user would know that they need to do this. And since we can’t tell whether a user has Outlook Express or not in advance, we can no longer use S/MIME to send messages.

There’s an even better solution though. Stop using boneheaded Microsoft products and get some real e-mail software. Sure, Microsoft may pay your bills now, but you’re digging your own grave in the long haul.

Update: To be fair, the full version of Microsoft Outlook does not exhibit this issue. But then again, it’s a commercial product. Also, there’s no official way to actually uninstall Outlook Express.