Many thanks for this.
Sadly now that I've checked it out as far as we can tell the smtp domain is the right one, or at least it is right on some of the returned messages, but it has opened up other avenues of thought.
We do think we have narrowed it down a bit now in that we set up a forum with three people and a hotmail.com and a hotmail.co.uk and they all went through. However further research seems to be implying that the messages coming back could be because hotmail thinks they are bulk messages which would make a sort of sense.
How many messages constitute bulk I wonder and is there any way we can tell hotmail that they are not 'bad' mail?
I'll keep plugging away at it and see what happens.
Thanks
Forum
Forum emails not going through, other emails are
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