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Message 1 of 5

winmail.dat issues since BT email service upgrade

Good Morning

Since the update of the BT email service I can no longer receive and read .pdf files.

When I receive a .pdf file to my btinternet account is appears as a winmail.dat file that I cannot open, download or read.

NOTE:- I have some historical .pdf files in my mail Inbox that previously read ok via webmail and outlook that now also report as winmail.dat files.

Any help to resolve this issue would be gratefully received.

Many thanks

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Message 2 of 5

Re: winmail.dat issues since BT email service upgrade

Hi @oliverd,

Welcome to the Community and thanks for taking the time to post.

Sorry that you are unable to open PDF files since the update to BT Mail.

We are yet to come across any other customers having this same issue so hopefully, it's just a one-off. 

Can you try and access BT Mail on a different device and let me know if you are having the same issue?



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Message 3 of 5

Re: winmail.dat issues since BT email service upgrade

Hi Matt

Many thanks for your response; currently I have the same issue on IPad, Iphone, x2 laptops (using Webmail) and a home PC using Outlook 2016.

Ironically, I still have the Yahoo app on my IPad, e-mails from May '20 in the app are showing attachments as .pdf files these same e-mails  show the attachments as  winmail.dat via Webmail / Outlook following service upgrade.

Kind regards


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Message 4 of 5

Re: winmail.dat issues since BT email service upgrade

There was a suggestion earlier this month that it could be due to "Rich Text Format" settings being different between sender and recipient.

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Message 5 of 5

Re: winmail.dat issues since BT email service upgrade


What is winmail.dat?
Here's a definitive resolution for the "winmail.dat" issue.

If you, as an Outlook user, send e-mail formatted as Rich Text (RTF), and you send it to a person whose mail client does not support RTF, then that person will receive a plain text message, and everything else - attachments included - will be wrapped up into an unreadable "winmail.dat" file.

There are two ways for Outlook users to prevent this from happening:

1.) When composing new messages, make sure to set the format to "Plain Text" (Format menu -> Plain Text).

2.) When sending to a recipient that you know has no RTF mail capabilities, modify the recipient's contact record to indicate this. Go to your address book, click once on a contact name, then click the "Properties" button. Then, click on the folder tab that says "Name," and at the bottom of the window you'll see a checkbox that says, "Send e-mail using plain text only." Check this box, save the changes, and you will be all set.

More info and links can be found in the Microsoft Support Knowledgebase:

Winmail.dat Attached to All Internet Messages Regardless of Setting on Client.

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