diff --git a/README.md b/README.md
index ce3a11f..8f95bc6 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,7 @@ None
  * `postfix_sasl_user` [default: `postmaster@{{ ansible_domain }}`]: SASL relay username
  * `postfix_sasl_password` [default: `k8+haga4@#pR`]: SASL relay password **Make sure to change!**
  * `postfix_smtpd_banner` [default: `$myhostname ESMTP $mail_name (Ubuntu)`]: Greeting banner **You MUST specify $myhostname at the start of the text. This is required by the SMTP protocol.**
+ * `postfix_compatibility_level` [optional]: With backwards compatibility turned on (the compatibility_level value is less than the Postfix built-in value), Postfix looks for settings that are left at their implicit default value, and logs a message when a backwards-compatible default setting is required (e.g. `2`, `Postfix >= 3.0`)
  * `postfix_disable_vrfy_command` [default: `false`]: Disable the `SMTP VRFY` command. This stops some techniques used to harvest email addresses
  * `postfix_message_size_limit` [default: `10240000`]: The maximal size in bytes of a message, including envelope information
  * `postfix_header_checks_database_type` [default: `regexp`]: The database type for use in `header_checks`
diff --git a/templates/etc/postfix/main.cf.j2 b/templates/etc/postfix/main.cf.j2
index e95fee7..c669210 100644
--- a/templates/etc/postfix/main.cf.j2
+++ b/templates/etc/postfix/main.cf.j2
@@ -18,6 +18,10 @@ append_dot_mydomain = no
 
 readme_directory = no
 
+{% if postfix_compatibility_level is defined %}
+compatibility_level = {{ postfix_compatibility_level }}
+{% endif %}
+
 # TLS parameters
 smtpd_tls_cert_file={{ postfix_smtpd_tls_cert_file }}
 smtpd_tls_key_file={{ postfix_smtpd_tls_key_file }}