concurring: The Commissioner does not contend that the first notice was sent to the “last known address” of the taxpayer. His point, as explained in the majority opinion, is that receipt of the notice by the taxpayer is sufficient. The taxpayer, under the circumstances of this case, was under no burden to show that the address to which the notice was sent was not the address last known to the Commissioner. The Commissioner makes no contention that it was the last known address. He refers to it merely as a “former address.” For these reasons I think the majority opinion is correct.