I'd have to look back at the article, but I believe the mail interception took place during the Bush-era warrant-less wiretapping. The FISA courts were created

I'd have to look back at the article, but I believe the mail interception took place during the Bush-era warrant-less wiretapping. The FISA courts were created to remedy the warrant-less part of that, though they don't really seem to have done much for the oversight concern that you mention. By this I mean to suggest that such interdiction may not necessarily be truly warrant-less if performed today, even if it is still shady and lacking in accountability.