Along with the issue with hotmail (on this forum) I have now discovered that a large number of the IPs in the range of Tiscali (unfortunately my ISP in the UK) are blacklisted by at least 3 databases in DNBSL. Range appears to be 88.108.0.0 - 88.111.255.255. I have not checked them all - before someone asks.
This was raised to 'second level' support at their end on Friday (which means I have to wait until at least Monday....) . Whether this has come about from something like the Hotmail spam filter or the IP range IS bad, I know not. Bit of a PITA!