diff --git a/entrypoint.sh b/entrypoint.sh
index d585478..10ac758 100644
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -77,33 +77,39 @@ cat > /etc/postfix/master.cf <<'EOF'
 EOF
 
 # SMTP configuration.
-if [ "${POSTFIX_SMTP_ENABLED}" = "yes" ]; then
-  cat >> /etc/postfix/master.cf <<'EOF'
+case "${POSTFIX_SMTP_ENABLED}" in
+  true|yes|on|1)
+    cat >> /etc/postfix/master.cf <<'EOF'
 smtp      inet  n       -       y       -       -       smtpd
   -o syslog_name=postfix/smtp
 
 EOF
-fi
+    ;;
+esac
 
 # Submission configuration.
-if [ "${POSTFIX_SUBMISSION_ENABLED}" = "yes" ]; then
-  cat >> /etc/postfix/master.cf <<EOF
+case "${POSTFIX_SUBMISSION_ENABLED}" in
+  true|yes|on|1)
+    cat >> /etc/postfix/master.cf <<EOF
 submission inet n       -       y       -       -       smtpd
   -o syslog_name=postfix/submission
   -o smtpd_tls_security_level=${POSTFIX_SUBMISSION_TLS_SECURITY_LEVEL}
 
 EOF
-fi
+    ;;
+esac
 
 # SSL encrypted SMTP configuration.
-if [ "${POSTFIX_SMTPS_ENABLED}" = "yes" ]; then
-  cat >> /etc/postfix/master.cf <<EOF
+case "${POSTFIX_SMTPS_ENABLED}" in
+  true|yes|on|1)
+    cat >> /etc/postfix/master.cf <<EOF
 smtps     inet  n       -       y       -       -       smtpd
   -o syslog_name=postfix/smtps
   -o smtpd_tls_wrappermode=${POSTFIX_SMTPS_TLS_WRAPPERMODE}
 
 EOF
-fi
+    ;;
+esac
 
 # Other internal services.
 cat >> /etc/postfix/master.cf <<EOF