Mac Mail email displays improperly in recipient Outlook client
I used Catalina's Mac Mail app to compose and send an email consisting of some text, an inline PNG graphic image banner, and an attached PDF file.
One recipient, who uses an Outlook email client on a Windows 10 PC, received my email but, instead of a formatted inline message, he received an empty message with three attachments: a PNG file, an HTML file containing the message text, and a PDF file.
I tried sending it via my Mac.com account and then separately via my gmail account. In each instance, the bad result was the same. What can I do?
MacBook Pro