Apparently the FBI NY Field Office obtained these emails weeks ago, the first of October in their investigation of Anthony Weiner. They just turned them over to Comey Thursday and Lynch/Obama have told Comey that he cannot have a warrant to look at them and told him to keep it quiet. The NY FBI agents had received permission from Weiner to search his phone...so they didn't need a warrant...soooooo, who knows what will happen next.
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Here is an article from The Hill explaining how the NY FBI investigators have had the emails for weeks.

FBI agents knew of emails weeks before Comey did: report
October 30, 2016, 01:36 pm
By Rebecca Savransky
http://thehill.com/blogs/ballot-box/presidential-races/303502-fbi-agents-knew-of-emails-weeks-before-comey-did-report#.WBY4IUiWDhc.twitter

FBI agents reportedly knew early this month about the new emails that the agency now says are "pertinent" to the investigation into Hillary Clinton's private server — but did not brief FBI Director James Comey until late last week.

Comey was reportedly told about the new messages on Thursday, The Washington Post reported.
On Friday, less than two weeks from Election Day, Comey sent a letter to lawmakers saying emails "pertinent" to the investigation of the former secretary of State had been discovered and the FBI would be reviewing them.

The FBI director said the team should "take appropriate investigative steps designed to allow investigators to review these emails."

The Washington Post reported that it is not clear why the FBI agents waited to brief Comey after discovering in early October the emails in question on a computer it seized in connection with a separate investigation.

The emails were discovered while look into former Rep. Anthony Weiner (D-N.Y.) for an alleged online relationship with a 15-year-old girl. Weiner is the estranged husband of longtime Clinton aide Huma Abedin.

In the letter Comey sent on Friday, he wrote the agency does not know "the significance of this newly discovered collection of emails." Yahoo News reported Saturday the FBI did not have a search warrant to review the newly obtained emails.

(snip)

Full article:
http://thehill.com/blogs/ballot-box/presidential-races/303502-fbi-agents-knew-of-emails-weeks-before-comey-did-report#.WBY4IUiWDhc.twitter