I'm not sure that I can't help you with all problems because I have no experience with iRedMail...
LibClamAV Error: cli_untgz: Wrote 0 instead of 512 (/tmp/clamav-8e62984769df2b4c1a50fe6eeb1b6a66/daily.mdb)
LibClamAV Error: cli_cvdload(): Can't unpack CVD file.
LibClamAV Error: Can't load /var/lib/clamav/daily.cvd: CVD extraction failure
ERROR: CVD extraction failure
Can you post the output of
One other thing : since I do all the admin stuff on my server trough ssh in root user, I don't know if I had done the right thing when I run the iRedMail script. I don't know all about the sudo su- thing in Debian, so since I was already root user, I didn't do the sudo su- thing when I ran the iRedMail script.
You don't need sudo su if you're logged in as root. This sudo su thing was introduced with Ubuntu where the root account is disabled by default - this is not the case for Debian.