I've been trying to come up with a practical solution, but I'm not sure there really is one. I could re-arrange the menu items so that "delete" is less likely to be accidentally clicked (and, therefore, more likely to be purposefully clicked). This could be done by either moving it so that the items on either side of it are either a separator or a pop-out menu; or it could be done by making it a pop-out menu itself (e.g. delete -> confirm). But I'm not sure that these are really practical for the original problem posted.
I took a look at some other clients:
Thunderbird -- pop-out / Delete / Separator
Gmail.com -- Archive / Delete / Mark as read
Outlook.com -- Separator / Delete / Archive
Ok, I have what I believe is a good compromise for your problem (e.g. a work-around) -- you can change the permissions of the folder to non-writable. You would need to do this for each accounts' "Archive" folder:
1) In PP, select an account and access the folder (Windows Explorer) by selecting main menu: View / Explore -> Archive folder
2) Go "up" a folder so that you can see the "Archive" folder
3) Using Windows Explorer: Right-click on the "Archive" folder and select "Properties"
4) Select the "Security" tab
5) Press "Edit"
6) Make sure "Authenticated Users" is selected on top (or whichever group is appropriate for your use-case)
7) In the bottom list, find "write" and tick the "deny" checkbox
8 ) Press OK
I would just use Windows explorer to navigate to any other Accounts' "Archive" folder instead of repeating from step #1. And, important, don't try to cut corners on the above instructions and write-protect a parent folder instead of each individual "archive" folder or you *will* run into issues.
Now, when you try to archive a message from that account, you'll get an error message.