Jonathan Stephens, permanent secretary at the DCMS, said Mr Smith was considered before the emails emerged to be someone who "understood and would abide by his proper role".
He told the inquiry the better the special adviser, the more reliable a guide they were to a Secretary of State's view.
"I think he was well tuned in to the Secretary of State's thinking," he said.
He went on:
The first suggestion that contacts went beyond what was proper was April 24 with the release of emails from Fred Michel and this was the first occasion I recall mention of Michel by name.
The following morning I told the Secretary of State I thought the number, extent, depth and tone of contacts supported by those emails went beyond what was acceptable.