Authorities arrested the woman after tracking the name and address used on the packages. But after the woman was arrested, the shipping agent said she wasn't the one who signed the shipping documents, the official said.
The release means investigators no longer have any suspects in custody in a suspected al-Qaida plot that authorities believe was intended to take down cargo jetliners.
The Yemeni official, who spoke on condition of anonymity because of the ongoing investigation, said investigators now believe someone stole her identity and used it to mail the bombs. Whoever mailed the bombs had used her name, address and telephone number, the official said.
The woman, an engineering student, was released on bail but cannot leave the country pending further questioning.
Matt Apuzzo contributed to this report.