Outlook sending imbedded images as text

[Invincible Sugar]

Hello, my supervisor at work is sending screenshots of our appointment schedule as images pasted into an email, using the snipping tool in Windows 10 to send the images via the current Office 365 version of Outlook.

 

Some recipients are receiving the image as intended, but some are getting this:

 

There doesn't appear to be any commonality between those receiving the email as text, as in, they aren't all gmail users, or mobile users, etc.

 

Any and all help would be greatly appreciated! Thank you!