Don't know what mail protocol Orange uses...
If it's IMAP, and it's configured that way in my app, then reading a message will mark it read on the server.
As for deleting goes, you can select one or more messages in a message list and choose "Delete now" from the "three dots" menu, rather than using the Trash can icon.
If "deleting now" is what you prefer, there is a way to select it in the account's Options and Folders -> Account options. Long press the account to open these settings.
