Emails on Mac look horrible (no HTML formatting)

Emails on Mac look horrible (no HTML formatting)

Hi there,

Just setting up some zoho hosted email accounts on a mac via IMAP and the downloaded emails look horrible - they are fine viewing them on the web so the emails aren't corrupted.
I've attached a screenshot - you can see the subject and sender is missing / corrupted and the message body is displaying plain text instead of HTML - some of the emails are just a jumble of characters (not even HTML)

Any ideas on how to fix?

This is happening in both outlook for mac and the inbuilt mail client