Email with hyperlink sent to Teams Channel are not parsing, and the attachements are showing as .dat

New Contributor

Email with hyperlink sent to Teams Channel are not parsing, and the attachments are showing as .dat instead of the regular attachment files.


On the attached image below is part of the signature of the sender along with some hyperlinks to social media. Line should say either just or and hyperlink to the company site, but instead its not.




2 Replies
Hi @New_Folder

Wow! Never thought I would see a winmail.dat issue when it comes to Teams

I used to work a ton with Exchange and used to handle loads of Exchange migrations heading up Pro Services for the business I work for. Winmail.dat was usually caused by the sender (in this case the sender to the Teams Channel email) either not disabling TNEF in their Outlook client, or on their Exchange Server

The guide I always used to use was this

I hope that helps to resolve your problem. The article will go into the why but basically go into the User's Outlook > Settings > Mail > Mail Format and ensure that this is converting to HTML. That fails, disable TNEF in the Registry and if they are using an Exchange Server disable it there too

Hope that helps to resolve your issue

Best, Chris

@Christopher Hoard 

Hey Chris!


I skim through the link you sent, though the workarounds are very easy to understand, I might get a lot of confused users asking me how to...


This issue just started last friday, 21-Aug-2020, but prior to that everything is working fine. Im just a regular user, do you think our admin might have change something in the deeper privileges? All of the users, including my emails are being formatted as plaintext (or being unformatted).


I'll be trying the workaround on the website, hopefully something works.



edit: ok, I just checked the workarounds. Nothing has been changed on our Email/Outlook settings. We/I don't have access to the properties of contacts or it has been update not to be editable probably due to company policy.


I really appreciate the response, Im still having this issue. I am suppose to present this new process, but it the results are showing these and I cannot fix it, I sure this won't get approved.


to add: sending email to email works OK, but sending email to Teams Channels converts the email to plain text