On Thu, Feb 09, 2012 at 01:00:33AM +0100, Chris wrote:
Feb 9 00:49:57 x800 postfix[1387]: warning: valid_hostname: invalid character 13(decimal): x800.mydomain.local?
13 is control-M.
One of your config files is in DOS format and has an embedded control-M in it. Check /etc/sysconfig/network. If you "vi" it, does it show ^M at the end, or does the bottom line say [dos] ?
When you find the file, "dos2unix" will fix it.