Postal rule technicality?

where does uk case law stand on the postal rule when an offer stipulates that acceptance must be recieved through post by the sales director, and the acceptance is recieved by the company, but not forwarded to director? i seem to recall hearing that it is binding (even when you apply Howell Securities v Hughes) because the court wont penalise someone for the internal mismanagement of another company, but i cant find ths point anywhere, nor a relevant case. hlep much appreciated