Mystery solved. There was a blanket ban: Having asked the question of the Adultwork help desk I was given the answer that they have an 'anti-abuse' system that scans all messaged and triggers if certain terms come up. Rather weirdly in my case it was the end of one sentence and the beginning of the next. This: “a bit. Do you”. [to do with being in said SP's city on work and wondered if she had availability].
'bit. Do' is a spam trigger. Who knew?
As a result there was a blanket ban on my outgoing messages. They have lifted the ban and I will try not to be so outrageous in my messages going forward....
