Subject to certain restrictions,
convolving on the right by a fixed function defines a bounded linear operator between
spaces of measures or functions over a locally compact group. For non-compact
groups we show that when the range and domain are different, such operators rarely
have closed range. Applications of these results are made to representation theory
for locally compact groups. We also prove a correspondence theorem for
strictly cyclic vectors for Banach algebras and those for certain closed left
ideals.