Look for an option or preference for that "feature" in that webmail portal software, '''while you're using Firefox'''. Some webmail software saves user preferences in Cookies in the browser being used to access their service; IE might have those Cookies, while Firefox may not - until you set your preferences again while using Firefox. Once saved, you wouldn't need to set those preferences again, unless you clear your Cookies. If that doesn't solve your issue, you might want to look at the Exchange webmail help pages or contact their support to see how to "fix" that for Firefox.