Following a server crash I started receiving errors as listed. Here is how I fixed it:
service postfix stop killall -9 postdrop postfix check service postfix start
If ‘postfix check’ returns errors – look through them and fix them one by one then run that command again to verify if everything is OK.
If you still having problems try:
chgrp -R postdrop /var/spool/postfix/public chgrp -R postdrop /var/spool/postfix/maildrop/ /etc/postfix/post-install upgrade-permissions /usr/sbin/postfix set-permissions