I do not know how many times I have to say it: Unless the hard drives in that server were incinerated into ashes then the data is recoverable.
I’m betting they are not the original hard drives. I’m sure the NSA or someone has access to all of the e-mails and has had them for some time. Remember the small leak when they were first turned over and the FBI said they accessed something off the drives. If they were replaced, I bet that the Hillary camp is sh!tting a brick.