I noticed that the version of clamav (0.90) in debian etch is sometime hanging randomly and mails are deferred and never delivered to the mailboxes. We can install clamav from the volatile repository to correct this problem. Here is what i did:
We need to add a line in /etc/apt/sources.list
vi /etc/apt/sources.list
Simply paste this line at the end of the file:
deb-src http://volatile.debian.org/debian-volatile sarge/volatile main contrib non-free
apt-get update
We first build all the dependency for clamav-daemon
apt-get build-dep clamav-daemon
Now we fetch the source of clamav-daemon and build the package
cd /usr/src
apt-get source clamav-daemon
cd clamav-0.92.1dfsg/
dpkg-buildpackage -uc -us -rfakeroot -nc
Then we just need to install the necessary packages
dpkg -i clamav-base_0.92.1dfsg-0volatile1_all.deb
dpkg -i libclamav3_0.92.1dfsg-0volatile1_i386.deb
dpkg -i clamav-daemon_0.92.1dfsg-0volatile1_i386.deb

That’s all ! Your antivirus is now updated and ready to scan mails