diff --git a/README.md b/README.md
index 955a64c..ffe51e3 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,16 @@ TLS and OpenDKIM support are optional.
 			-v /path/to/certs:/etc/postfix/certs \
 			--name postfix -d catatnight/postfix
 	```
+4. Customize configs for postfix
+
+	```bash
+	$ sudo docker run -p 25:25 \
+			-e maildomain=mail.example.com -e smtp_user=user:pwd \
+			-e postconf=key:value \
+			--name postfix -d hkcomori/postfix
+	# Set multiple configs: -e postconf=key1:value1,key2:value2,...,keyN:valueN
+	# Restrictions: key, value must not contain `,`, `:`
+	```
 
 ## Note
 + Login credential should be set to (`username@mail.example.com`, `password`) in Smtp Client
diff --git a/assets/install.sh b/assets/install.sh
index 0b2aaff..bcd83e9 100755
--- a/assets/install.sh
+++ b/assets/install.sh
@@ -68,6 +68,13 @@ if [[ -n "$(find /etc/postfix/certs -iname *.crt)" && -n "$(find /etc/postfix/ce
   postconf -P "submission/inet/smtpd_recipient_restrictions=permit_sasl_authenticated,reject_unauth_destination"
 fi
 
+#############
+# postconf
+#############
+echo "$postconf" | tr , \\n | while IFS=':' read -r _key _value; do
+  postconf -e $_key=$_value;
+done
+
 #############
 #  opendkim
 #############