For a while I have experienced an issue with iPad where a single email account will only download headers (IMAP) and the body of the email exhibits the message above in the subject line. I have deleted and added back with no change. I've Googled this and no solution has worked. Then in January the iPad stopped even downloading headers and the message 'This message has no content'.
I recently bought an iPhone and exactly the same thing happened when I added it. However, in both cases I can send emails and the iPhone does show latest emails.
I have another account on the same SM server on a different domain and that works perfectly.
I set up the account both in Thunderbird and Outlook or Mac and these work ok.
So the specific problem is with Mac Mail for that account. I even deleted lots of old emails in case it was a size issue.
Any assistance would be welcome.