diff --git a/README.md b/README.md
index 3b57f90..eb3dddc 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,11 @@ The following configuration options are mandatory in each quarantine section:
 * **smtp_port**  
   SMTP port
 
+The following configuration options are optional in each quarantine section:
+* **reject_reason**  
+  Reason to return to the client if action is set to reject.
+
+
 ### Quarantine types
 * **NONE**  
   Original e-mails scrapped, sent to nirvana, black-holed or however you want to call it.
diff --git a/docs/pyquarantine.conf.example b/docs/pyquarantine.conf.example
index 26f42bb..84f4faa 100644
--- a/docs/pyquarantine.conf.example
+++ b/docs/pyquarantine.conf.example
@@ -70,6 +70,12 @@ quarantine_directory = /var/lib/pyquarantine/spam
 #
 action = discard
 
+# Option: reject_reason
+# Notes:  Optionally set the reason to return if action is set to reject.
+# Values: [ REASON ]
+#
+reject_reason = Message rejected
+
 # Option: notification
 # Notes:  Set the notification type.
 # Values: [ email | none ]
diff --git a/pyquarantine/__init__.py b/pyquarantine/__init__.py
index 1363fa9..c7d8c54 100644
--- a/pyquarantine/__init__.py
+++ b/pyquarantine/__init__.py
@@ -181,6 +181,8 @@ class QuarantineMilter(Milter.Base):
                 quarantine = self._get_preferred_quarantine()
                 self.logger.info("{}: {} matching quarantine is '{}', performing milter action {}".format(self.queueid, self.global_config["preferred_quarantine_action"],
                         quarantine["name"], quarantine["action"].upper()))
+                if quarantine["action"] == "reject":
+                    self.setreply("554", "5.7.0", quarantine["reject_reason"])
                 return quarantine["milter_action"]
 
             return Milter.CONTINUE
@@ -249,6 +251,8 @@ class QuarantineMilter(Milter.Base):
             quarantine = self._get_preferred_quarantine()
             self.logger.info("{}: {} matching quarantine is '{}', performing milter action {}".format(self.queueid, self.global_config["preferred_quarantine_action"],
                     quarantine["name"], quarantine["action"].upper()))
+            if quarantine["action"] == "reject":
+                self.setreply("554", "5.7.0", quarantine["reject_reason"])
             return quarantine["milter_action"]
 
         except Exception as e:
@@ -314,6 +318,17 @@ def generate_milter_config(configtest=False, config_files=[]):
             if option not in config.keys():
                 raise RuntimeError("mandatory option '{}' not present in config section '{}' or 'global'".format(option, quarantine_name))
 
+        # check if optional config options are present in config
+        defaults = {
+            "reject_reason": "Message rejected"
+        }
+        for option in defaults.keys():
+            if option not in config.keys() and \
+                    option in global_config.keys():
+                config[option] = global_config[option]
+            if option not in config.keys():
+                config[option] = defaults[option]
+
         # set quarantine name
         config["name"] = quarantine_name