This is an error with amavisd .

Check the proper hostname, that could be guilty..

vi /etc/amavisd.conf

and check for hostname

Or,

vi /etc/postfix/main.cf

find content_filter and comment that out ( Temp solution )

Amavis dead but subsys locked :

rm /var/amavis/amavisd.pid

rm /var/amavis/amavisd.lock