Here is my attempt to summarize the events surrounding the released email from Snowden to NSA lawyers. Please correct me if I have made a mistake (as I often do).
Prior to the release of the email, Snowden claimed that in emails to NSA lawyers, he was "raising concerns about the NSA’s interpretations of its legal authorities.” According to Snowden, one specific concern was that some high officials in the NSA believed that classified executive orders could override federal law. In the email the NSA released, Snowden asked NSA lawyers about this very issue. Specifically, he asked about training materials which seemed to him to contradict the principle that federal law overrides executive orders. Someone from the NSA’s Office of General Council responded that executive orders do not override federal law, which makes it look like Snowden’s concern was satisfied.
But Snowden also claims that he expressed his concern about the NSA’s understanding of its legal authorities in correspondence “with the Signals Intelligence Directorate’s Office of Compliance, which believed that a classified executive order could take precedence over an act of Congress . . .” We are not in a position to know if that claim is true. Hopefully, the NSA will release more emails (assuming they exist), but I doubt the NSA would want the public to know that some high NSA official believed that executive orders could override federal law and that Snowden questioned that belief. So we end up in a strange situation. If Snowden is lying, there are no additional emails to release, but we have no way of knowing that there are none. And if Snowden is telling the truth, then the NSA probably won’t release the emails that would vindicate him. Either way, we may well end up being left in the dark.
Personally, I doubt that Snowden is lying about corresponding with the Signals Directorate’s Office of Compliance about this issue. But I am not in a position to know for sure.