diff --git a/Block/Checkout/LayoutProcessor.php b/Block/Checkout/LayoutProcessor.php
index 2b246de..7f9dc4f 100644
--- a/Block/Checkout/LayoutProcessor.php
+++ b/Block/Checkout/LayoutProcessor.php
@@ -106,12 +106,12 @@ public function modifyStreetUiComponents($addressResult)
         $lineCount = 0;
 
         while($lineCount < 4){
- 
+
             $lineNumber = $lineCount+1;
 
             if(isset($addressResult['street']['children'][$lineCount])){
                 $label = $this->addressLineHelper->getLineLabel($lineNumber);
-                
+
                 if ( $this->addressLineHelper->isLineEnabled($lineNumber)) {
                     $addressResult['street']['children'][$lineCount]['label'] = $label;
                     $addressResult['street']['children'][$lineCount]['additionalClasses'] = 'experius-address-line-one';
@@ -125,6 +125,4 @@ public function modifyStreetUiComponents($addressResult)
 
         return $addressResult;
     }
-
-
 }
diff --git a/Helper/Data.php b/Helper/Data.php
index a152100..629c972 100644
--- a/Helper/Data.php
+++ b/Helper/Data.php
@@ -81,7 +81,7 @@ public function getValidationClassesForLine($lineNumber)
         return $validationClassesString;
     }
 
-    public function getValidationClassesAsArrayForLine($lineNumber) 
+    public function getValidationClassesAsArrayForLine($lineNumber)
     {
         $group = "experius_address_lines/experius_address_line{$lineNumber}";
 
@@ -102,9 +102,29 @@ public function getValidationClassesAsArrayForLine($lineNumber)
         if($this->isLineRequired($lineNumber)){
             $validationClassesArray['required-entry'] = 1;
         }
+        if ($this->getEnablePOBoxRule()) {
+            $validationClassesArray = $this->getPOBoxRule($validationClassesArray);
+        }
+        $this->_logger->debug(print_r($validationClassesArray, true));
         return $validationClassesArray;
     }
 
+    public function getEnablePOBoxRule()
+    {
+        return !$this->getModuleConfig("shipping_po_box", "experius_address_lines");
+    }
+
+    public function getPOValidationRegex()
+    {
+        return '/^parcel.*|^locker.*|^box.*|.*po\s*box.*|.*p[\.\s]o\.?\sbox.*/i';
+    }
+
+    public function getPOBoxRule($existingClasses)
+    {
+        $existingClasses['po-box-validation'] = true;
+        return $existingClasses;
+    }
+
     /**
      * Return form attribute IDs by form code
      *
diff --git a/README.md b/README.md
index da1a816..60c39ff 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-**Experius Address Lines,**
+**Experius Address Lines**
 
 Adds labels to address lines and adds configuration per address line.
 
@@ -8,6 +8,8 @@ Configuration Per Line
 - Label
 - Validation Classes
 
+Also has an option for disabling PO Boxes in the address
+
 Stores > Configuration > Customers > Customer Configuration > Address Lines
 
 **Screenshots**
diff --git a/etc/adminhtml/system.xml b/etc/adminhtml/system.xml
old mode 100755
new mode 100644
index 0b717d7..358cacc
--- a/etc/adminhtml/system.xml
+++ b/etc/adminhtml/system.xml
@@ -105,6 +105,10 @@
                         <comment>Necessary for registrion page and address edit.</comment>
                     </field>
                 </group>
+                <field id="shipping_po_box" showInDefault="1" showInStore="1" showInWebsite="1" sortOrder="1000" translate="label" type="select">
+                    <label>Allow PO Boxes in the Addresss lines?</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                </field>
             </group>
         </section>
     </system>
diff --git a/etc/config.xml b/etc/config.xml
old mode 100755
new mode 100644
index 6018499..2b09530
--- a/etc/config.xml
+++ b/etc/config.xml
@@ -1,5 +1,6 @@
 <?xml version="1.0" ?>
-<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
     <default>
         <customer>
             <experius_address_lines>
@@ -31,6 +32,7 @@
                     <line_required></line_required>
                     <line_validation_classes></line_validation_classes>
                 </experius_address_line4>
+                <shipping_po_box>1</shipping_po_box>
             </experius_address_lines>
         </customer>
     </default>
diff --git a/etc/module.xml b/etc/module.xml
old mode 100755
new mode 100644
diff --git a/view/frontend/layout/customer_account_create.xml b/view/frontend/layout/customer_account_create.xml
old mode 100755
new mode 100644
diff --git a/view/frontend/layout/customer_address_form.xml b/view/frontend/layout/customer_address_form.xml
old mode 100755
new mode 100644
diff --git a/view/frontend/requirejs-config.js b/view/frontend/requirejs-config.js
new file mode 100644
index 0000000..4199e60
--- /dev/null
+++ b/view/frontend/requirejs-config.js
@@ -0,0 +1,9 @@
+var config = {
+  config: {
+    mixins: {
+      'Magento_Ui/js/lib/validation/validator': {
+        'Experius_AddressLines/js/validator-mixin': true
+      }
+    }
+  }
+};
\ No newline at end of file
diff --git a/view/frontend/templates/experius/customer/address/edit.phtml b/view/frontend/templates/experius/customer/address/edit.phtml
index 8a7d5be..4344a31 100644
--- a/view/frontend/templates/experius/customer/address/edit.phtml
+++ b/view/frontend/templates/experius/customer/address/edit.phtml
@@ -55,7 +55,10 @@
         <?php endif; ?>
         <div class="field street required">
             <label for="street" class="label"><span><?php /* @escapeNotVerified */ echo __('Street Address') ?></span></label>
-            <div class="control">
+            <?php if ($this->helper('Experius\AddressLines\Helper\Data')->getEnablePOBoxRule()): ?>
+              <div class="info">PO Boxes not allowed</div>
+            <?php endif; ?>
+          <div class="control">
                 <label class="label" for="street_<?php /* @escapeNotVerified */ echo $_i ?>">
                     <span><?php /* @escapeNotVerified */ echo $this->helper('Experius\AddressLines\Helper\Data')->getLineLabel($_i) ?></span>
                 </label>
@@ -178,3 +181,20 @@
         }
     }
 </script>
+
+<?php if ($this->helper('Experius\AddressLines\Helper\Data')->getEnablePOBoxRule()): ?>
+<script type="text/javascript">
+  require([
+    'jquery',
+    'jquery/validate',
+    'mage/translate'
+  ], function ($) {
+    $.validator.addMethod(
+      'po-box-validation', function (value) {
+        var re = <?php echo $this->helper('Experius\AddressLines\Helper\Data')->getPOValidationRegex(); ?>;
+        return !re.test(value);
+      }, $.mage.__("We don't ship to PO Boxes, Parcel Lockers, or any postal service. Courier only.")
+    );
+  });
+</script>
+<?php endif; ?>
diff --git a/view/frontend/templates/experius/customer/form/register.phtml b/view/frontend/templates/experius/customer/form/register.phtml
index 87971be..eafa07d 100644
--- a/view/frontend/templates/experius/customer/form/register.phtml
+++ b/view/frontend/templates/experius/customer/form/register.phtml
@@ -78,7 +78,10 @@
             <?php endif; ?>
             <div class="field street required">
                 <label for="street" class="label"><span><?php /* @escapeNotVerified */ echo __('Street Address') ?></span></label>
-                <div class="control">
+                <?php if ($this->helper('Experius\AddressLines\Helper\Data')->getEnablePOBoxRule()): ?>
+                  <div class="info">PO Boxes not allowed</div>
+                <?php endif; ?>
+              <div class="control">
                     <label class="label" for="street_<?php /* @escapeNotVerified */ echo $_i ?>">
                         <span><?php /* @escapeNotVerified */ echo $this->helper('Experius\AddressLines\Helper\Data')->getLineLabel($_i) ?></span>
                     </label>
@@ -194,7 +197,9 @@
 <script>
 require([
     'jquery',
-    'mage/mage'
+    'jquery/validate',
+    'mage/mage',
+    'mage/translate'
 ], function($){
 
     var dataForm = $('#form-validate');
@@ -220,8 +225,17 @@ require([
     <?php endif ?>
     }).find('input:text').attr('autocomplete', 'off');
 
+    <?php if ($this->helper('Experius\AddressLines\Helper\Data')->getEnablePOBoxRule()): ?>
+    $.validator.addMethod(
+      'po-box-validation', function (value) {
+        var re = <?php echo $this->helper('Experius\AddressLines\Helper\Data')->getPOValidationRegex(); ?>;
+        return !re.test(value);
+      }, $.mage.__("We don't ship to PO Boxes, Parcel Lockers, or any postal service. Courier only.")
+    );
+    <?php endif; ?>
 });
 </script>
+
 <?php if ($block->getShowAddressFields()): ?>
 <script type="text/x-magento-init">
     {
diff --git a/view/frontend/web/css/source/_module.less b/view/frontend/web/css/source/_module.less
index b6ecbbd..e96b4ca 100644
--- a/view/frontend/web/css/source/_module.less
+++ b/view/frontend/web/css/source/_module.less
@@ -5,7 +5,7 @@
 & when (@media-common = true) {
   .experius-address-lines {
 
-    .field{
+    .field {
       margin: 0 0 20px;
     }
 
@@ -13,5 +13,12 @@
       display: none !important;
     }
 
+    label + .info {
+      font-weight: normal;
+      font-style: italic;
+      margin-bottom: 1em;
+    }
+
   }
+
 }
\ No newline at end of file
diff --git a/view/frontend/web/js/validator-mixin.js b/view/frontend/web/js/validator-mixin.js
new file mode 100644
index 0000000..25f0942
--- /dev/null
+++ b/view/frontend/web/js/validator-mixin.js
@@ -0,0 +1,19 @@
+define([
+  'jquery',
+  'moment'
+], function ($, moment) {
+  'use strict';
+
+  return function (validator) {
+
+    validator.addRule(
+      'po-box-validation',
+      function (value) {
+        var re = /^parcel.*|^locker.*|^box.*|.*po\s*box.*|.*p[\.\s]o\.?\sbox.*/i
+        return !re.test(value);
+      }, $.mage.__("We don't ship to PO Boxes, Parcel Lockers, or any postal service. Courier only.")
+    );
+
+    return validator;
+  };
+})