Updating mail/calendar invites

[Haleth]

Hello. I made a small script so my minimap border turns red when I have pending invites, green when I have new mail, orange when both, and black when none of them.

local f=CreateFrame("Frame")
f:SetScript("OnEvent", function(self, event, ...)
   local inv = CalendarGetNumPendingInvites()
    if inv > 0 then
		if HasNewMail() then
			CreateBG(Minimap):SetTexture(1, .5, 0)
		else
        		CreateBG(Minimap):SetTexture(1, 30/255, 60/255)
		end
    else
    		if HasNewMail() then
			CreateBG(Minimap):SetTexture(0, 1, 0)
  		else
        		CreateBG(Minimap):SetTexture(0, 0, 0)
    end
end
end)

The problem is though, it only updated on a reloadui. How can I make this update on its own?