Thanks for the information.
Perhaps the spam filtering on the new version of exchange is blocking the messages, Matt might be able to tell us something about that.
Another question I forgot to ask, Does the sender get any type of non delivery or “bounce” message.
Is this one or two Houghton user not receiving the emails or have you had questions from many users?
I’ll send you a message from my Hotmail to test perhaps you could also tell me some other users and I will send to them also.