Weird auto-correction in Office for Mac?
I know this is an old post, but I think I may just have figured it out.
I am using Outlook on PC, but I have had the exact same issue, such as "for the" becoming "fort he".

I have German and English languages installed and I believe this is the source of the problem (and it goes back at least 14 years if you try Google. Good bug fixing MS).

Anyway, the solution I found was to turn off "Detect Language Automatically" in the email editor. In the PC version this can be found on the Review ribbon under Language. I hope the Mac version has a similar layout.



This has appeared to work so far. It's a pain because changing languages in email will require a manual flip each time, but if I can avoid oft he, fort he, fort hat, etc. then it is worth it.

Hope this helps, even so late after the fact!