Issue with displaying emails

Hi, there is an issue with displaying emails. Some parts of the received email were displayed correctly while others ended up as attachments. I checked how this message appears in another email client, and it displays correctly in its entirety. Is this a matter of email settings or is it an error in app?

If the message has an htm attachment, then this is probably an email from an Apple app.

Unfortunately that format is not supported, so can’t be displayed. As far as I know MS Outlook can’t display them either.

even if part of the message is displayed correctly?