Lost document saved as email attachment

I've been working for a couple of hours on a word document, which I saved regularly but stupidly forgot to save it to my desktop - i.e. I just saved the temporary file version that opens directly from the email. I've found various help pages online for such a situation but none of them seems to work. I'm using Mac OS10.13.6 and Outlook 16.40. Does anyone know whether this file could be somewhere retrievable, and if so how I find it?

Thanks

Nigel