Customize OXMail (open-xchange mail)

Ox doesn't natively sync its follow up, responded to, and forwarded flags with the same standard flags IMAP, iphone mail app, Outlook etc. use. We want to customize OX so when OX's flags (eg. the red flag) is interchangeable (synced) with the follow up flag on ios mail app and vise versa (when you click on "Flag" to designate a follow up email) and the same when an email is responded to or forwarded in ios mail app or vise versa.