# cat /etc/passwd | grep "amavis\|clamav"

clamav:x:101:102:Clam Anti Virus Checker:/var/clamav:/sbin/nologin
amavis:x:102:103:Amavis email scan user:/var/amavis:/bin/sh

In addition, the clamav user should automatically have been added to the amavis group:

# groups clamav

clamav : clamav amavis

If not, you can manually add clamav to the amavis group:

# gpasswd -a clamav amavis

Finally, three new services should have been added to the system

# chkconfig --list | grep "amavisd\|clamd\|spamassassin"

amavisd             0:off   1:off   2:on    3:on    4:on    5:on    6:off
clamd                 0:off   1:off   2:on    3:on    4:on    5:on    6:off
spamassassin    0:off   1:off   2:off    3:off    4:off    5:off    6:off