interface has no rights to show logs

Unable to read /var/log/mail.log -rw-r----- 1 syslog adm 35170208 Jul 10 19:59 /var/log/mail.log

Unable to read /var/log/mail.warn -rw-r----- 1 syslog adm 0 Jul 6 06:47 /var/log/mail.warn

Unable to read /var/log/mail.err -rw-r----- 1 syslog adm 0 Dec 13 2007 /var/log/mail.err

Unable to read /var/log/messages -rw-r----- 1 syslog adm 910106 Jul 10 19:59 /var/log/messages