To delete the Postfix mail queue use the following command:

root@deb:~# postsuper -d ALL
postsuper: Deleted: 5 messages
root@deb:~#

You can also use man postsuper command for more options.

Postfix stable release 2.8.0 is available. This release continues the move towards improving code and documentation, and making the system better prepared for changes in the threat environment.

• The postscreen daemon (a zombie blocker in front of Postfix) is now included with the stable release. postscreen now supports TLS and can log the rejected sender, recipient and helo information.

  See the POSTSCREEN_READM file for recommended usage scenarios.

• Support for DNS whitelisting (permit_rhswl_client), and for pattern matching to filter the responses from DNS white/blacklist
  servers (e.g.,  reject_rhsbl_client zen.spamhaus.org=127.0.0.[1..10]).
• Improved message tracking across SMTP-based content filters; the after-filter SMTP server can log the before-filter queue ID (the XCLIENT protocol was extended).
• Read-only support for sqlite databases. See sqlite_table(5) and SQLITE_README.
• Support for ‘footers’ that are appended to SMTP server “reject” responses. See “smtpd_reject_footer” in the postconf(5) manpage.

No functionality has been removed, but it is a good idea to review the RELEASE_NOTES file for the usual minor incompatibilities or limitations.

You can find Postfix version 2.8.0 at the mirrors listed at http://www.postfix.org/.

The same code is also available as Postfix snapshot 2.9-20110120.
Updated versions of Postfix version 2.7, 2.6, 2.5 and 2.4 will be released as time permits. Support for Postfix 2.4 will end soon.