Greetings all, I've got a new Exchange 2013 setup and external internet users have been reporting that attachments they receive from internal users are showing only as winmail.dat (why does this problem still exist?!?) In Exchange 2010 I had a transport rule that sent *everything* to the internet as plain-text to stop this happening, but I can't seem to find any info on how to do this in Exchange 2013. There's no obvious options in the ECP, so I'm guessing it's a powershell command?

Set-RemoteDomain -Identity <Name of Domain> -TNEFEnabled $falseDetails here:http://support.microsoft.com/kb/2487954?wa=wsignin1.0Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you.

Set-RemoteDomain -Identity <Name of Domain> -TNEFEnabled $falseDetails here:http://support.microsoft.com/kb/2487954?wa=wsignin1.0Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you.

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(Sorry, busy weekend) That powershell was the way to do it. I had found the article about Set-RemoteDomain but with many other options, but it wasn't as clear to which one of those options was the same as "send as plain text". I assume settings like this will be added to the ECP over time. For the record, I just set it for all external email. I might take some time to tweak to work out just the right format that works, but for the time being plain text is better than winmail.dat Set-RemoteDomain -Identity * -TNEFEnabled $false

We too have experienced same issue, Server 2012 running exchange 2013. I have been working with Microsoft support and they had me run this command "Set-RemoteDomain -Identity * -TNEFEnabled $false" which is referenced above. I can confirm this did resolve my issue with the winmail.dat sending with attachments. However, once this was enabled we were having delivery failure notifications and having large number of emails (going to external users) that would get stuck in the submission que. The error on them would be "A Storage Transient Failure Has Occurred during content Conversion". Once again I started working with Microsoft and received a different support person. He had me run the following command "Set-RemoteDomain -Identity * -TNEFEnabled $true", and after that had me restart the transport services. Immediately I thought to myself, darn, I don't know which issue I would rather have. It is consistent in our environment that enabling or disabling the TNEF has side effects which impact our end users greatly. I am again putting in a support request with Microsoft, I just thought I would share my experience with running (or seeing) this command ran.

I have had the same issue. lots of failed messages in the mail queue and I had to set Set-RemoteDomain -Identity * -TNEFEnabled $true to resolve this problem. however once the issue is resolved some internet recipients receive winmail.dat files this can be resolved with Set-RemoteDomain -Identity * -TNEFEnabled $false but then back to messages stuck in queue. I will update is CU1 fixes issue with having TNEF set to false.