Thank you for that quick response, jbbarlow3.

I'd like to help and make sure your employees receive their paystubs in PDF format.

I agree with BigRedConsulting, this is is a known issue for Microsoft outlook if the recipient's email client is not capable of receiving rich text format (.rtf).

To fix this, we can change the message format in Outlook. You can choose from either HTML to a plain text or plain text to HTML. This will prevent it from attaching a Winmail.dat file when you send an email. You can check out the details steps here: Change the message format to HTML, Rich Text Format, or plain text.

If you've already tried changing it but still encountering the same issue, I'd suggest using other email besides an Outlook email. Here's an article for more information and the steps on how to set up your email service in QuickBooks Desktop.

Additionally, if only one or some of your employees  experience this issue, it can be due to a problem on the receiving end. Certain security features and mail filters may detect this as a mass emailing (spam). Thus, the emails must be adjusted accordingly. 

You may also consider setting up and inviting your employees to QuickBooks workforce. This way, your employees can see their pay stubs and W-2s online. 

Get back to me if you still have other questions or clarifications about paystubs. I'll be here to answer them. Have a wonderful day!