Sale boss Steve Diamond says they were justified in signing Denny Solomona but Castleford believe the legal saga could happen again.
Australia utility back James O'Connor signs for Premiership side Sale Sharks from Toulon on a three-year contract.
Castleford Tigers accept a compensation payment "in excess of £200,000" for the transfer of Denny Solomona to Sale Sharks.
Edinburgh and London Irish are to meet holders Stade Francais in the Pool stage of next season's European Challenge Cup.
Audio & Video
Sale Sharks’ former Wales scrum-half Mike Phillips says the time is right to retire as he looks forward to the final game of his career.
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