Postfix MTA update - fix security vulnerabilities

Postfix MTA updated to fix security vulnerabilities.

- Incorrectly checks of the ownership of a mailbox is now fixed. It will increase some security. If you run postfix on your server, you should upgrade to these updated packages.

Patch Postfix under Debian / Ubuntu Linux:
1 - Update the internal database:
# apt-get update
2 - Install corrected Postfix package
# apt-get upgrade

Patch Postfix under RHEL / CentOS Linux:
For RHEL and CentOS 5:
# yum update

Under RHL5:
# up2date -u