It’s the online equivalent of police breaking down the wrong door.

Court documents show that a typo caused federal investigators in Milwaukee to go through an innocent person’s e-mail account as they tried to track down an alleged Russian spammer.

An FBI agent says in a search-warrant affidavit that as soon as he discovered his mistake he stopped reviewing the e-mails, sealed them and sought a new search warrant for the correct address.

Investigators were trying to find 23-year-old Oleg Nikolaenko, a Russian believed to be running one of the world’s largest spam networks. His e-mail address was ddarwinn(at)gmail.com, but when an FBI agent applied for a search warrant he omitted the second ‘n’.