New Celtic manager Tony Mowbray has held talks with Boruc, who has extra competition for his place after international team-mate Lukasz Zaluska's arrival on freedom of contract from Dundee United.
He joins fellow new arrival Ryan Esders who signed a permanent contract with Quins earlier this week after a successful loan spell from Hull Kingston Rovers.
The former Rotherham and York manager was handed a three-year contract by Mansfield on his arrival in the summer, although a protracted takeover of the club was only completed earlier this week.
Marks' arrival in Plymouth has led to Brian McKenzie being released from his contract with the Raiders, ensuring the club stay within the limit of three foreign players.
But universities are clearly becoming desperate, and the arrival of at least four firms of ambulance-chasing lawyers keen to persuade students to sue for breach of contract can only make them more so.