Emails are not showcasing the same emails.

Question

Is anybody running into the issue of different emails showing on different platforms (Browser and App).
Ex. An executive assistant clears out emails at the end of each day. On their end, it shows the emails have been deleted. On the Account Holder's end, the email is still there days, weeks, even months later.

Is there a solution as to why this is not synced?

Any assistance is greatly appreciated!