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Problem with Attachments sent to Yahoo Email

I have a problem sending email attachments from my Outlook account to various Yahoo email accounts.  The email arrives fine, but the attachments are somehow corrupted into something that cannot be opened.  Below is a screen shot of the message I get when I attempt to download a PDF file, though the same happens with Word attachments.  And there is no "open" option available.  It seems as though all the attachments are renamed to some version of "di-mail.ymail.com":

Yahoo Attachment Problem
Please help.

Thanks,

Phil
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strivoliIT Manager
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Commented:
I see you get winmail.dat. If this is it and you are running your own Mail Server (such as Exchange) you should change Exchange behaviour with TNEF.
David FavorFractional CTO
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Commented:
Verify if some email you get with .pdf attachments provides the open option or all .pdf attachments produce this behavior.
Jackie Man IT Manager
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Commented:
Are you using Yahoo! Mail app or Chrome browser?

Author

Commented:
Strivoli, I don't understand what you said.  David, all PDF and Word attachments produce the same result.  Jackie, I get my Yahoo mail from the Yahoo mail site using Chrome.
Jackie Man IT Manager
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Commented:
How were the emails being sent?

Using Outlook.com from a Chrome browser?

Author

Commented:
The emails were sent from Outlook 365.  To check out whether the sending device could be the culprit, I tried sending an email to the Yahoo account from Gmail, and the attachment worked.  So how do I fix the problem with attachments sent from my Outlook to my Yahoo accounts?
IT Manager
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Commented:
You need to review the properties of the contact (Yahoo account) in Outlook 365 and change the recommended setting is Let Outlook decide...

https://www.slipstick.com/problems/outlook-is-sending-winmail-dat-attachments/

Winmail.dat

Author

Commented:
Thank you.