  We apply L.~Schwartz' theory of vector valued distributions in order to
simplify, unify and generalize statements about convolvability of
distributions, their regularization properties and topological properties of
sets of distributions. The proofs rely on propositions on the multiplication of
vector-valued distributions and on the characterization of the spaces
$\mathcal{O}_{M}(E,F)$ and $\mathcal{O}_{C}'(E,F)$ of multipliers and
convolutors for distribution spaces $E$ and $F$.
