That’s because Mail-in-a-box uses apt-get -qq -s upgrade to get a list of what packages would be upgraded if you would run apt-get upgrade. Usually the output of this command would be empty when there are no packages to upgrade, but since Canonical decided to add advertisements to it, the output looks like this:
apt-get -qq -s upgrade
Try Ubuntu Pro beta with a free personal subscription on up to 5 machines.
Learn more at https://ubuntu.com/pro
…so Mail-in-a-Box assumes that the two lines are referring to packages that should be updated, when they are in fact just advertisements for Ubuntu Pro.