by Tony Rushin

ttpicThis is definitely not a tip about the New Orleans Saints and their silly “who dat” phrase.  C’mon – we’re Falcons’ fans here.  Rise up!

This tip is about .DAT files:  specifically winmail.dat files that you may have received or that may have been reported to you from an email recipient.  Winmail.dat files look like gibberish to the recipient.

Inadvertently Sending Winmail.dat Emails

If you use Outlook, and a Microsoft Exchange server (in the cloud or at your company) sends and manages your email, then you may inadvertently be sending winmail.dat files to recipients who don’t use Outlook.  You really don’t know you’re doing it unless the recipient tells you.  If that happens, ask the recipient to take a screen shot of the email they received and send it – along with the email you sent – to your IT support person immediately.

This is a problem that can be easily fixed on your Microsoft Exchange server.  It has to do with Rich Text Formatting (RTF) and the Transport Neutral Encapsulation Format (TNEF) that’s used to send those emails (sorry to get all nerdy on you).  The TNEF settings need be correctly configured so non-Outlook recipients get HTML formatted emails (instead of RTF) so they can actually read the email or attachment.  I’m not going to get into all of the technical details but it’s a pesky problem because it can seem random and specific per recipient.  If you’re an attorney interacting with a new client this can be frustrating – especially when deadlines are looming and communication between the law firm and the client is crucial.

If your IT support person doesn’t know how to fix the issue, here’s a Microsoft resource and another resource to send their way.  In addition, here’s the method many of our engineers use (note: the fix is applied on a per email address basis since you don’t want to force the entire firm to send all messages in plain text or RTF):

Modify the recipient’s entry in the Personal Address Book

The sender can use the following steps to remove the RTF format from the recipient attribute in the Personal Address Book:

  1. On the Tools menu, click Address Book.
  2. In Show Names From, click the Personal Address Book.
  3. Select the addressee that you want to set as plain text, and then click Properties on the File menu.
  4. In the SMTP-General tab, click to clear the Always send to this recipient in Microsoft Exchange rich text format check box, and then click OK.

Receiving Winmail.dat Emails

ttpic2The surest way to fix the problem is to contact the sender and have them fix it on their end (see above).  However, what if the IT department on the sending end isn’t as responsive as you’d like them to be?  Are there any ways you can take matters into your own hands and fix the problem on your end?  The answer, thankfully, is “yes” but the receiver-side fixes aren’t always foolproof.  If you receive winmail.dat emails from a frequent sender then it’s worth the effort to get it fixed on the sender end.  Here’s a short blog with some good receiver-side solutions.

Now if you get a winmail.dat email, don’t get frustrated and say “who dat” or “what dat” – take action and “do dat”!

Network 1 Consulting is a 15-year-old, IT Support company in Atlanta, GA.  We become – or augment – the IT department for professional services companies: law firms, medical practices and financial services firms.  Our IT experts can fix computers – but what our clients really value are the industry-specific best practices we bring to their firms.  This is especially important with technology, along with regulations and cyber threats, changing so rapidly.  We take a proactive approach to helping our clients use technology to gain and keep their competitive advantage.

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