How is winmail.dat my problem?

Misconfigured Outlook clients used to be the bane of my existance. And, occasionally can still be, in 2012. Which is pretty astounding, when you think about it.

The background is pretty simple, really. Outlook clients send e-mail using a Microsoft proprietary format, which certainly isn’t MIME. That is pretty amazing that someone thought that everyone, everywhere, would use Outlook to send mail to other Outlook users.

Try explaining to a customer that those files aren’t a Notes/Domino problem Sure, they understand,  but they want them to go away. So, it becomes my problem.

Thankfully, there are two notes.ini settings that you can apply to your SMTP server. Or server’s. Whatever the case may be.

Open the Domino Administrator. Go to the Servers tab, click on Server Console.

Enter “set config TNEFEnableConversion=1” then click either Send or hit enter.

Enter “set config TNEFKeepAttachments=1” then click either Send or hit enter.

To enable the setting to take effect immediately, enter “tell router update config” then click either Send or hit enter.

There, now someone else’s problem has been resolved on your servers. You’re welcome.

Here is a handy TechNote that explains the cause and resolution in a little more detail.

This behavior is due to messages being sent from Exchange without MIME encoding turned on. Winmail.dat is attached to the message in uuencoded format. Information on how to prevent winmail data being sent to Internet users from MS Exchange is documented and publicly available from the Microsoft Support Web page, in the Microsoft Knowledge Base, article number Q138053

 

Author: Gregg Eldred

This is a weblog with some basis in IBM/Lotus Notes & Domino software, when I feel like it or think of something that might be interesting. Other than that, we'll see where this goes. The views expressed in this blog are mine alone, and do not reflect the views of NextStep Technologies, LLC. If you think otherwise, you are mistaken. © 2003-2020 NextStep Technologies, LLC. All rights reserved. The rights to all logos, images, etc., are owned by their respective owners.

5 thoughts on “How is winmail.dat my problem?”

  1. I found a free program that unpacks the winmail.dat files. I usually have the user forward me the email, I unpack it, and send them back whatever was attached. This makes my life much simpler. Thanks!

    1. Steve, I thought about mentioning something along that line but decided against it. Asking users (or Admins) to process those files just didn’t seem right to me. However, you are correct, there are several tools out there, including one from OpenNTF that handles them quite well.

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