This lede from the New York Times's Charlie Savage says it all:
A newly declassified report by the National Security Agency’s inspector general suggests that the government is receiving far less data from Americans’ international Internet communications than privacy advocates have long suspected.
According to a recently declassified Inspector General report, when the NSA conducts Internet surveillance pursuant to its Section 702 authority, companies are only required to hand over emails to, from, or about the NSA's foreign targets and not all data crossing their servers. The Times notes that the report suggests "that the government supplies its foreign target's 'selectors' — like email address — to the network companies that operate the Internet, and they sift through the raw data for any messages containing them, turning over only those."
The full set of documents obtained by the Times can be found below. The 2015 IG Report on the Implementation of §215 of the USA Patriot Act and §702 of the FISA Amendments Act of 2008, to which these revelations correspond, begins on page 147.