Thanks for taking the trouble to bring this to our attention.

Having pursued this matter, it became clear that a supposedly opt-in list purchased by a marketing company used by our customer was nothing of the sort.

I am satisfied that the contract between the company and those selling the lists has been ceased, and there will be no further repetition of this problem from this source.

I will continue to monitor SPAMCOP reports sent to us to ensure this remains the case.