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Our accounting program Exact Accounting automatically sends email statements to customers via Outlook 2013. The statement is comprised of a subject line, an attached pdf, and a blank body. Multiple customers are receiving the winmail.dat file instead of the pdf.

These are the steps I have taken, that have not solved the issue:

  1. Outlook is configured to send HTML.

  2. I have used powershell to set the Exchange Online server to default to TNEF to false.

  3. I have used powershell to add domain objects for 2 different customer domains to default their TNEF to false.

Any suggestions please? Why is the exchange server still encapsulating in this TNEF - what am I missing?

Thanks.

HBruijn
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leo_cape
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2 Answers2

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I had to set the email type as Plain Text, this worked. However, the MS documentation clearly states that either HTML or PLAIN text corrects this problem - which apparently is incorrect.

leo_cape
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This problem exists for decades, as you might have detected by searching the internet for solutions.

I talked to a Microsoft technician and he sent me this:

$UserCredential = Get-Credential
Set-ExecutionPolicy RemoteSigned

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection

Import-PSSession $Session

Set-RemoteDomain Default -TNEFEnabled $false

The important line is the very last one. It's a global setting that disables a sending format that causes the 'winmail.dat' issue for everybody. Or something along those line …

The technician assured me that this would have zero side effects, apart from never sending 'winmail.dat' files again. I can confirm, that I have yet to encounter a case where that change does something I was not expecting it to do.

Daniel
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