...Just in case it offers any clue, when a new email does come through, the constant 'receiving messages...' tally increases by one, i.e. if it had previously been saying 'receiving message 1 of 1' for an hour, after the email has come through, it changes to '2 of 2' (or more, depending on the number of emails that have arrived) even though the new message(s) has/have already been downloaded to the in box.