Due to a change of service provider and the usual dns changes, I hit a postfix startup crash where service postfix start would crash with an cryptic message about postalias and segfault. (several google entries, none of the suggested fixes worked)
Here's the fix:
In main.cf, search for 'myhostname' (usually reserved for virtual servers)
and uncomment it, then replace myhostname = xxx.xxx.xxx with my.fqdnhostname.com

# The myhostname parameter specifies the internet hostname of this
# mail system. The default is to use the fully-qualified domain name
# from gethostname(). $myhostname is used as a default value for many
# other configuration parameters.
#
myhostname = my.fqdnhostname.com <<here with your real fqdn hostname

VIOLA!
start postfix and everything is right with the world again.

xcamel