The properties of quantum channels with diagonal Kraus operators are examined.
These are exactly the channels which allow full transmission of classical information.
The condensed matrix is presented. The quantum channel has capacity zero iff the condensed matrix has full rank, otherwise it
can transmit at least 1 qubit per use.
A tight bound on the number of error operators a random quantum channel may have and still be correctable is given for
both real and complex diagonal channels.