Using backports.org is very simple:

If you want to get announcements about security updates on backports.org subscribe to the backports-security-announce mailinglist.

1. Add this line

deb www.backports.org/debian lenny-backports main contrib non-free

to your /etc/apt/sources.list.

2. Run apt-get update

3. All backports are deactivated by default. If you want to install something from backports run:

apt-get -t lenny-backports install “package”

Of course, you can use aptitude as well:

aptitude -t lenny-backports install “package”

You can also use pinning:

Then you have to set a higher priority for each backport, yes that means every backport, also for every dependency. For mutt, you have to add these lines:

Package: mutt
Pin: release a=lenny-backports
Pin-Priority: 999

to your /etc/apt/preferences (if you haven’t use pinning before, the file has to be created).

After running apt-get update run apt-get install mutt as usual.

If you want apt to verify the downloaded backports you can import backports.org archive’s key into apt:

apt-get install debian-backports-keyring

or

gpg --keyserver hkp://subkeys.pgp.net --recv-keys 16BA136C
gpg --export 16BA136C | apt-key add -

or

wget -O - backports.org/debian/archive.key | apt-key add -

If you want to get your packages from backports upgraded automatically the following entry in /etc/apt/preferences should be sufficient:

Package: *
Pin: release a=lenny-backports
Pin-Priority: 200