diff --git a/ChangeLog b/ChangeLog
index 4e99dd3e..d8b47795 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
 iRedMail-1.4:
+    * DROPPED distribution release:
+        - Debian 9 (stretch). Please use Debian 10 instead.
+
     * Fixed issues:
         - Fail2ban can not store banned IP address when its country name
           contains quotes.
diff --git a/conf/dovecot b/conf/dovecot
index 493c3d3f..6d2132d2 100644
--- a/conf/dovecot
+++ b/conf/dovecot
@@ -79,8 +79,8 @@ if [ X"${DISTRO}" == X'RHEL' ]; then
 elif [ X"${DISTRO}" == X'DEBIAN' -o X"${DISTRO}" == X'UBUNTU' ]; then
     export DOVECOT_DELIVER_BIN='/usr/lib/dovecot/deliver'
 
-    # Debian 9, Ubuntu 18.04.
-    if [ X"${DISTRO_CODENAME}" == X'stretch' -o X"${DISTRO_CODENAME}" == X'bionic' ]; then
+    # Ubuntu 18.04.
+    if [ X"${DISTRO_CODENAME}" == X'bionic' ]; then
         export DOVECOT_VERSION='2.2'
     fi
 elif [ X"${DISTRO}" == X'FREEBSD' ]; then
diff --git a/conf/global b/conf/global
index b2ff224c..38fe4bac 100644
--- a/conf/global
+++ b/conf/global
@@ -236,7 +236,7 @@ export UNSUPPORTED_RELEASE='NO'
 if [ X"${KERNEL_NAME}" == X'LINUX' ]; then
     export DISTRO_VERSION=$(awk -F'"' '/^VERSION_ID=/ {print $2}' /etc/os-release)
 
-    # Debian: 9: stretch, 10: buster
+    # Debian: 10: buster
     # Ubuntu: 18.04: bionic, 20.04: focal
     export DISTRO_CODENAME=$(awk -F'=' '/^VERSION_CODENAME=/ {print $2}' /etc/os-release)
 
@@ -478,15 +478,9 @@ elif [ X"${DISTRO}" == X'DEBIAN' -o X"${DISTRO}" == X'UBUNTU' ]; then
     # Directory /etc/default/ on Debian/Ubuntu.
     export ETC_SYSCONFIG_DIR='/etc/default'
 
-    # iptables rule file.
-    export FIREWALL_RULE_CONF="${ETC_SYSCONFIG_DIR}/iptables"
-    export FIREWALL_RULE_CONF6="${ETC_SYSCONFIG_DIR}/ip6tables"
-
-    if [ X"${DISTRO_CODENAME}" == X'buster' ]; then
-        export USE_NFTABLES='YES'
-        export NFTABLES_CONF='/etc/nftables.conf'
-        export FIREWALL_RULE_CONF="${NFTABLES_CONF}"
-    fi
+    export USE_NFTABLES='YES'
+    export NFTABLES_CONF='/etc/nftables.conf'
+    export FIREWALL_RULE_CONF="${NFTABLES_CONF}"
 
     # Directory used to store SSL/TLS key/cert file.
     export SSL_FILE_DIR="/etc/ssl"
diff --git a/conf/php b/conf/php
index 190e060e..f5e87e06 100644
--- a/conf/php
+++ b/conf/php
@@ -41,10 +41,7 @@ if [ X"${DISTRO}" == X'RHEL' ]; then
     export PHP_FPM_PID_FILE='/run/php-fpm/php-fpm.pid'
 
 elif [ X"${DISTRO}" == X'DEBIAN' -o X"${DISTRO}" == X'UBUNTU' ]; then
-    if [ X"${DISTRO_CODENAME}" == X'stretch' ]; then
-        # Debian 9
-        export PHP_VERSION='7.0'
-    elif [ X"${DISTRO_CODENAME}" == X'buster' ]; then
+    if [ X"${DISTRO_CODENAME}" == X'buster' ]; then
         # Debian 10
         export PHP_VERSION='7.3'
     elif [ X"${DISTRO_CODENAME}" == X'bionic' ]; then
diff --git a/conf/postgresql b/conf/postgresql
index 95fb6637..b4f52fb1 100644
--- a/conf/postgresql
+++ b/conf/postgresql
@@ -39,10 +39,7 @@ if [ X"${DISTRO}" == X'RHEL' ]; then
     export PGSQL_CONF_PG_HBA="${PGSQL_DATA_DIR}/pg_hba.conf"
 
 elif [ X"${DISTRO}" == X'DEBIAN' -o X"${DISTRO}" == X'UBUNTU' ]; then
-    if [ X"${DISTRO_CODENAME}" == X'stretch' ]; then
-        # Debian 9
-        export PGSQL_VERSION='9.6'
-    elif [ X"${DISTRO_CODENAME}" == X'bionic' ]; then
+    if [ X"${DISTRO_CODENAME}" == X'bionic' ]; then
         # Ubuntu 18.04
         export PGSQL_VERSION='10'
     elif [ X"${DISTRO_CODENAME}" == X'buster' ]; then
diff --git a/functions/clamav.sh b/functions/clamav.sh
index 6b7dadf5..59f47964 100644
--- a/functions/clamav.sh
+++ b/functions/clamav.sh
@@ -57,8 +57,7 @@ clamav_config()
 
     # Enable AllowSupplementaryGroups
     perl -pi -e 's/^(AllowSupplementaryGroups.*)/#${1}/' ${CLAMD_CONF}
-    if [ X"${DISTRO_CODENAME}" != X'stretch' \
-        -a X"${DISTRO_CODENAME}" != X'bionic' \
+    if [ X"${DISTRO_CODENAME}" != X'bionic' \
         -a X"${DISTRO_CODENAME}" != X'disco' \
         -a X"${DISTRO}" != X'FREEBSD' ]; then
         echo 'AllowSupplementaryGroups true' >> ${CLAMD_CONF}
diff --git a/functions/dovecot.sh b/functions/dovecot.sh
index c8dd271d..080ce787 100644
--- a/functions/dovecot.sh
+++ b/functions/dovecot.sh
@@ -176,8 +176,7 @@ dovecot_config()
     perl -pi -e 's#PH_SSL_CIPHERS#$ENV{SSL_CIPHERS}#' ${DOVECOT_CONF}
 
     # Distros ships newer openssl which doesn't support SSLv2 anymore.
-    if [ X"${DISTRO}" == X'DEBIAN' -a X"${DISTRO_CODENAME}" == X'stretch' ] \
-        || [ X"${DISTRO}" == X'UBUNTU' -a X"${DISTRO_CODENAME}" == X'bionic' ] \
+    if [ X"${DISTRO}" == X'UBUNTU' -a X"${DISTRO_CODENAME}" == X'bionic' ] \
         || [ X"${DISTRO}" == X'RHEL' -a X"${DISTRO_VERSION}" == X'8' ]; then
         perl -pi -e 's#^(ssl_protocols).*#ssl_protocols = !SSLv3#' ${DOVECOT_CONF}
     fi
diff --git a/functions/packages.sh b/functions/packages.sh
index 53f92070..56c44a74 100644
--- a/functions/packages.sh
+++ b/functions/packages.sh
@@ -364,7 +364,7 @@ install_all()
             [[ X"${DISTRO_VERSION}" == X'7' ]] && ALL_PKGS="${ALL_PKGS} php-pear-Net-IDNA2"
         elif [ X"${DISTRO}" == X'DEBIAN' -o X"${DISTRO}" == X'UBUNTU' ]; then
             if [ X"${BACKEND}" == X'OPENLDAP' ]; then
-                if [ X"${DISTRO_CODENAME}" == X"bionic" -o X"${DISTRO_CODENAME}" == X"stretch" ]; then
+                if [ X"${DISTRO_CODENAME}" == X"bionic" ]; then
                     ALL_PKGS="${ALL_PKGS} php-net-ldap3"
                 else
                     ALL_PKGS="${ALL_PKGS} php-ldap"