I and my wife are getting jumbled email content in the Mail app on our iPhones

iPhone 13 Pro Max IOS 17.4.1

Both my partner’s and my identical IPhones have been jumbling emails occasionally during the last few months. We have used Outlook emails with the iPhone Mail app for some years without trouble until recently.

Searching just now for an email from a friend brings up the body text of her email sent and received 3 days ago through my personal email with the sender, address and subject of an email from a news service received this morning through my university email account. I repeat the search for her first name and the same error occurs.

This happens sporadically to my partner within her single email account.

Explanation and ideas please.

[Re-Titled by Moderator]