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How to fix the winmail.dat attachment issue on office 365

Posted under Office 365 by ifoundafix

The other day I Found A Fix for a recent problem I was having. The issue is described as follows;

Some of my recipients were reporting issues that mails I sent to them contained the winmail.dat file ONLY. This issue relates to how Office 365 sets the default attachment format to TNEF. Apple products and other non microsoft email clients in particular seemed to have problems reading my mails. The solution is to run the commands below in from the PowerShell fo Office 365.

To do this I found the following steps were required.

Note: Powershell commands are in bold. Type enter after each line item

1. Run Powershell as administrator.

2. Login to Office 365 with $cred=Get-Credential

3. Enter the admin username and password i.e name@domainname.com and password.

4. $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic -AllowRedirection

If you receive an error with the above command type Set-ExecutionPolicy Unrestricted . Next, try the above command again.

5. Import-PSSession $Session

6. Set-RemoteDomain Default -TNEFEnabled $false

7. Remove-PSSession $Session


I hope you too have found a fix

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