I don't want OO to ever open a file in read only mode UNLESS the file has read only windows properties...
As far as I know, this is exactly the situation you have now.
If you're reading an email that has an attachment, and you save the attachment as a file in (e.g.) "My Documents", and OOo opens that document in read-only mode, then there are only two possibilities: either the email client has saved the file without write permissions, or the document itself was marked by its author as "read-only". Since the second option seems unlikely, I strongly suspect that your email client is responsible for the "read-only" status.
An attachment to an email message has no permission settings at all, so the only way the attachment can have any properties (other than the system defaults) is if the email software sets them.
Try saving an attachment to a file, in a folder that you normally use for documents, and check the file's properties. I think you'll find that the mail client has made the file read-only.
BTW, if you open a document directly from the email client, and OOo opens it as "read-only", then you are safe to simply do that--you don't have to save the attachment first. The danger occurs when the email client doesn't
mark the temporary file as "read-only" and the user goes ahead and edits the temporary file, which is then deleted by the email client.
So, when you double-click on the attachment, and OOo opens a file as "read-only", you can simply click on the "Edit File" button on the toolbar. OOo will remind you that the document can't be changed, and allow you to edit a copy instead. Then, when you save the document, OOo will prompt for a location and you can save it in a safe place.
I'm not saying that's the best approach--it's better to understand the problem and deal with it directly by saving the attachment. I'm only saying that it's a simpler alternative that should be just as safe.
This all works so poorly because email was never designed as a file-transfer, or file-sharing, tool. It works better in MS Office because MS controls the entire stack (OS, email client, word processor), so they can make it work any way they like. Everything's rosy.