A bidding war could be in the offing for Courier Corp. After signing a definitive purchase agreement with Quad/Graphics January 16, the company confirmed Tuesday it has received an unsolicited takeover proposal from R.R. Donnelley.

In its bid, Donnelley is offering to acquire Courier for $23 per share in cash or Donnelley stock. The offer could by prorated “in the event that shareholders elect to receive more than approximately 49% cash or more than approximately 51% stock,” Courier said.

Quad/Graphic is offering $20.50 per share in a combination of cash and stock. In a statement, Courier said that despite the new offer, the board, which gave its unanimous backing to the Quad/Graphics deal, continues to support the Quad/Graphics offer. The company noted, however, the “consistent with its fiduciary duties,” Courier’s board, “in consultation with its independent legal and financial advisors, will carefully review and consider the RR Donnelley proposal.”

The Donnelley proposal is subject to, among other things, various closing conditions, Courier shareholder approval and regulatory approvals.