Hi there,
It's vital that your recipients receive their files using .pdf instead. I'd be happy to share more info about this.
This is a known issue for Microsoft outlook if the recipient's email client is not capable of receiving rich text format (.rtf). To learn more about email message formats, check out How email message formats affect Internet email messages in Outlook.
Quick tip
If only one or some customers experience this issue, it can be due to a problem on the receiving end. Certain security and mail filters may detect these emails as mass emailing (spam) and must be adjusted accordingly.
Here are some solutions to this:
Solution 1: Change the message format in Outlook
Choosing either HTML or plain text can prevent Outlook from attaching a Winmail.dat file when you send an email. To learn more about the detailed steps, check out Change the message format to HTML, Rich Text Format, or plain text.
Solution 2: Use email other than Outlook
For detailed instructions on how to use another email, check out Set up your email service in QuickBooks Desktop.
In case you have other questions, feel free to contact our support team using this link here.