Some emails forwarded from Outlook don't show full message

By default, Mail collapses conversations.

In Mail, click on Inbox. Go to the menu bar and choose View > Expand All Conversations.

This change will only affect the folder that was chosen. In order for all folders to behave this way, you have to choose them one at a time and then apply the same menu choice to each one.

I am unable to duplicate your issue. The free version of Outlook is what I use. I can forward emails I originally opened in Outlook to either another email address I use, or to my wife's email. Either way, we have no trouble viewing the forwarded email in Apple's Mail app.

But if I'm reading your previous statement correctly, it sounds like you're specifically using Microsoft's Outlook mail server. We don't. Since we're not seeing any issues moving emails between our Gmail and secondary email accounts, I would have to presume the MS mail server is somehow causing the problem.

Hmm. I don't have a solution then. We do those kind of forwarding options somewhat regularly and have no trouble opening anything in Mail.