That is NOT correct.my host files says: 192.168.2.101 mail mail.freeos.co.uk
To the best of my knowledge that is correct; so why would I change that and what would you suggest I put there!
192.168.2.101 mail.freeos.co.uk mail
Which is not really the point - a careful reading of my last post will show that I told you, if you want to change the hostname, edit the /etc/HOSTNAME file. But fixing /etc/hosts will actualy fix your problem.