Little blue box in mail

Little blue box? If you can post a screenshot (suitably redacted, using Markup Tools, to remove personal or sensitive information), contributors may have a better understanding of your issue.

Take a screenshot on your iPad - Apple Support

You can post your screenshot using the image button at the bottom of the message editing window:

Many tanks for the screenshot.

The little-blue box, with a question mark, indicates a placeholder for an embedded image that cannot be downloaded and displayed by the Mail App.

There are no settings that you can refine to remedy display of the missing image/logo. Note, however, that many automated messages sent by websites, such as your illustration, may contain a link to view the message in a web-browser.