  We provide a new derivation of the anisotropies of the cosmic microwave
background (CMB), and find an exact expression that can be readily expanded
perturbatively. Close attention is paid to gauge issues, with the motivation to
examine the effect of super-Hubble modes on the CMB. We calculate a transfer
function that encodes the behaviour of the dipole, and examine its
long-wavelength behaviour. We show that contributions to the dipole from
adiabatic super-Hubble modes are strongly suppressed, even in the presence of a
cosmological constant, contrary to claims in the literature. We also introduce
a naturally defined CMB monopole, which exhibits closely analogous
long-wavelength behaviour. We discuss the geometrical origin of this
super-Hubble suppression, pointing out that it is a simple reflection of
adiabaticity, and hence argue that it will occur regardless of the matter
content.
