Thanks to all of you, the plot thickens! By shuffling the message to go between Outbox and Drafts, eventually, after a few attempts, the message shows up in the outbox in italic format, not bold, upright type and will send, sometimes seems to work better if there is an 'unsendable' message already in the Outbox. Very hit and miss. Unable to get through to ISP Tech Support to check settings at the moment, being Monday they are very busy.