(See Andy’s solution in the Comments suggesting ‘Try 193.252.22.138 instead of smtp.orangehome.co.uk’. I have tested this and it works.)
Before saying anything else:
Avoid Orange Home Broadband service like the plague if you use either Microsoft Outlook or Windows Vista.
Having spent the last 3 hours on the phone with OrangeHome (0870 010 2462), with 5 different Technical [...]