Someone crook pretended to be Britney Spears' manager and got her record label to send a bunch of yet-to-be-released music ... TMZ has learned..

According to docs obtained by TMZ ... the suspect impersonated Larry Rudolph, Brit's longtime manager, and emailed RCA Records to ask for tracks that at the time were unreleased. The person went so far as to create larry.rudolph@aol.com ... which is not Larry's actual email address.

Didn't matter ... RCA reps got duped and uploaded 49 digital files.

In all, law enforcement says the culprit nabbed 12 tracks intended for Britney's album, "Glory," which was released in August 2016 ... shortly after this caper.

Law enforcement obtained search warrants in October 2016 and June 2017 to search AOL and Microsoft records for the suspect's email account -- and they now have a suspect. They say he's an attorney who's studying intellectual property law at UCLA. There goes the Dean's List ... allegedly.