It didn't download packages at all, run below command to fetch them:

# cd /path/to/iRedMail-x.y.z/
# cd pkgs/
# bash get_all.sh

ok thanks for your help...FIXED!

# cd /path/to/iRedMail-x.y.z/
# cd pkgs/
# bash get_all.sh

Validate Packages ...md5sum: pkgs/postfix-policyd_1.82-2_amd64.deb: No such file or directory
pkgs/postfix-policyd_1.82-2_amd64.deb: FAILED open or read
md5sum: pkgs/libmail-dkim-perl_0.36-0.1~bpo50+1_all.deb: No such file or directory
pkgs/libmail-dkim-perl_0.36-0.1~bpo50+1_all.deb: FAILED open or read
md5sum: pkgs/python-jinja2_2.2.1-1~bpo50+1_amd64.deb: No such file or directory
pkgs/python-jinja2_2.2.1-1~bpo50+1_amd64.deb: FAILED open or read
md5sum: pkgs/python-netifaces_0.5-1_amd64.deb: No such file or directory
pkgs/python-netifaces_0.5-1_amd64.deb: FAILED open or read
md5sum: pkgs/python-webpy_0.32+dak1-1_all.deb: No such file or directory
pkgs/python-webpy_0.32+dak1-1_all.deb: FAILED open or read
md5sum: pkgs/dovecot-common_1.1.16-1~bpo50+1_amd64.deb: No such file or directory
pkgs/dovecot-common_1.1.16-1~bpo50+1_amd64.deb: FAILED open or read
md5sum: pkgs/dovecot-imapd_1.1.16-1~bpo50+1_amd64.deb: No such file or directory
pkgs/dovecot-imapd_1.1.16-1~bpo50+1_amd64.deb: FAILED open or read
md5sum: pkgs/dovecot-pop3d_1.1.16-1~bpo50+1_amd64.deb: No such file or directory
pkgs/dovecot-pop3d_1.1.16-1~bpo50+1_amd64.deb: FAILED open or read
md5sum: misc/phpMyAdmin-2.11.10-all-languages.tar.bz2: No such file or directory
misc/phpMyAdmin-2.11.10-all-languages.tar.bz2: FAILED open or read
md5sum: misc/postfixadmin_2.3.tar.gz: No such file or directory
misc/postfixadmin_2.3.tar.gz: FAILED open or read
md5sum: misc/phpldapadmin-1.2.0.5.tgz: No such file or directory
misc/phpldapadmin-1.2.0.5.tgz: FAILED open or read
md5sum: misc/iRedAdmin-0.1.3.tar.bz2: No such file or directory
misc/iRedAdmin-0.1.3.tar.bz2: FAILED open or read
md5sum: misc/iRedAPD-1.3.3.tar.bz2: No such file or directory
misc/iRedAPD-1.3.3.tar.bz2: FAILED open or read
md5sum: misc/Net_LDAP2-2.0.9.tgz: No such file or directory
misc/Net_LDAP2-2.0.9.tgz: FAILED open or read
md5sum: WARNING: 14 of 15 listed files could not be read
        [ FAILED ]
< ERROR > MD5 check failed. Check your rpm packages. Script exit ...