You have multiple email address' configured in their outlook.
When using apps such as Zoom to send emails directly to a patient. The email address that the app sends from is not correct and the "From" field cannot be changed.
The issue here is 3rd party apps look at the primary email configured in your outlook and use that when sending emails.
The way these app's use the outlook API, it prevents you from changing the the "From" Email address.
As seen in the image above, the "From" email is greyed out and normally prevents you changing the "From" Email address.
Open control panel, open your mail preferences.
In mail 32 check what the default email address is under the E-mail & Data File tabs.
Both of these tabs must have the same default settings.
After changing these settings, close the mail configuration window.
Open the 3rd party app again (ie. Zoom) and run a test to confirm the new settings are now working.
* NB: You may need to close and re open outlook for the changes to take effect.