diff --git a/NEWS b/NEWS
index a444225db..85f64f0d1 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ Enhancements
  - [web] AngularJS optimizations in Mail module
  - [web] AngularJS optimization of color picker
  - [web] improve display of tasks status
+ - [web] added custom fields support from Thunderbird's address book
 
 Bug fixes
  - [web] respect SOGoLanguage and SOGoSupportedLanguages (#4169)
diff --git a/UI/Contacts/UIxContactEditor.m b/UI/Contacts/UIxContactEditor.m
index 52851f87f..f9f1ffeaf 100644
--- a/UI/Contacts/UIxContactEditor.m
+++ b/UI/Contacts/UIxContactEditor.m
@@ -337,11 +337,13 @@ static Class SOGoContactGCSEntryK = Nil;
 
 - (void) setAttributes: (NSDictionary *) attributes
 {
-  CardElement *element;
-  NSArray *elements, *values;
   NSMutableArray *orgs, *categories;
+  NSDictionary *customFields;
+  NSArray *elements, *values;
   NSCalendarDate *date;
+  CardElement *element;
   id o;
+
   unsigned int i, year, month, day;
 
   [card setNWithFamily: [attributes objectForKey: @"c_sn"]
@@ -485,6 +487,38 @@ static Class SOGoContactGCSEntryK = Nil;
       [card setCategories: categories];
     }
 
+  customFields = [attributes objectForKey: @"customFields"];
+  if (customFields && [customFields isKindOfClass: [NSDictionary class]])
+    {
+      if ((o = [customFields objectForKey: @"1"]))
+        {
+          elements = [card childrenWithTag: @"custom1"];
+          [card removeChildren: elements];
+          [card addElementWithTag: @"custom1"  ofType: nil  withValue: o];
+        }
+
+      if ((o = [customFields objectForKey: @"2"]))
+        {
+          elements = [card childrenWithTag: @"custom2"];
+          [card removeChildren: elements];
+          [card addElementWithTag: @"custom2"  ofType: nil  withValue: o];
+        }
+
+      if ((o = [customFields objectForKey: @"3"]))
+        {
+          elements = [card childrenWithTag: @"custom3"];
+          [card removeChildren: elements];
+          [card addElementWithTag: @"custom1"  ofType: nil  withValue: o];
+        }
+
+      if ((o = [customFields objectForKey: @"4"]))
+        {
+          elements = [card childrenWithTag: @"custom4"];
+          [card removeChildren: elements];
+          [card addElementWithTag: @"custom1"  ofType: nil  withValue: o];
+        }
+    }
+
   [card cleanupEmptyChildren];
 }
 
diff --git a/UI/Contacts/UIxContactView.m b/UI/Contacts/UIxContactView.m
index bfec54742..6eaf282c1 100644
--- a/UI/Contacts/UIxContactView.m
+++ b/UI/Contacts/UIxContactView.m
@@ -270,14 +270,15 @@
  * @apiSuccess (Success 200) {Object[]} [urls]             URLs
  * @apiSuccess (Success 200) {String} urls.type            Type (e.g., personal or work)
  * @apiSuccess (Success 200) {String} urls.value           URL
+ * @apiSuccess (Success 200) {Object[]} customFields       Custom fields from Thunderbird
  */
 - (id <WOActionResults>) dataAction
 {
-  id <WOActionResults> result;
-  id o;
+  NSMutableDictionary *customFields, *data;
   SOGoObject <SOGoContactObject> *contact;
+  id <WOActionResults> result;
   NSArray *values;
-  NSMutableDictionary *data;
+  id o;
 
   contact = [self clientObject];
   card = [contact vCard];
@@ -355,6 +356,23 @@
   if ([contact hasPhoto])
     [data setObject: [self photoURL] forKey: @"photoURL"];
 
+  // Custom fields from Thunderbird
+  customFields = [NSMutableDictionary dictionary];
+  if ((o = [[card uniqueChildWithTag: @"custom1"] flattenedValuesForKey: @""]) && [o length])
+    [customFields setObject: o  forKey: @"1"];
+
+  if ((o = [[card uniqueChildWithTag: @"custom2"] flattenedValuesForKey: @""]) && [o length]) 
+    [customFields setObject: o  forKey: @"2"];
+
+  if ((o = [[card uniqueChildWithTag: @"custom3"] flattenedValuesForKey: @""]) && [o length])
+    [customFields setObject: o  forKey: @"3"];
+
+  if ((o = [[card uniqueChildWithTag: @"custom4"] flattenedValuesForKey: @""]) && [o length])
+    [customFields setObject: o  forKey: @"4"];
+
+  if ([customFields count])
+    [data setObject: customFields  forKey: @"customFields"];
+
   result = [self responseWithStatus: 200
                           andString: [data jsonRepresentation]];
 
diff --git a/UI/Templates/ContactsUI/UIxContactEditorTemplate.wox b/UI/Templates/ContactsUI/UIxContactEditorTemplate.wox
index 184b2efca..12a890ee1 100644
--- a/UI/Templates/ContactsUI/UIxContactEditorTemplate.wox
+++ b/UI/Templates/ContactsUI/UIxContactEditorTemplate.wox
@@ -348,6 +348,38 @@
               </div>
             </div>
 
+	    <!-- custom fields -->
+            <div class="section">
+              <div class="attr" ng-repeat="(key, value) in editor.card.customFields">
+                <div layout="row" layout-align="start center">
+                  <md-button class="md-icon-button" type="button" ng-click="editor.deleteCustomField(key)">
+                    <md-icon>remove_circle</md-icon>
+                  </md-button>
+                  <md-input-container flex="20">
+                     <label>
+                       <var:string label:value="Type"/>
+                     </label>
+                     <input type="text" readonly="readonly" ng-value="key"/>
+                  </md-input-container>
+                  <md-input-container class="md-flex">
+                    <label>
+                      <var:string label:value="Custom Value"/>
+                    </label>
+                    <input type="text" ng-model="editor.card.customFields[key]"/>
+                  </md-input-container>
+                </div>
+              </div>
+              <div class="md-layout-margin" layout="row"
+                   layout-align="start center" ng-show="editor.canAddCustomField()">
+                <md-button class="md-icon-button" type="button" ng-click="editor.addCustomField()">
+                  <md-icon>add_circle</md-icon>
+                </md-button>
+                <label class="button-label">
+                  <var:string label:value="New Custom Value"/>
+                </label>
+              </div>
+            </div>
+
             <!-- note -->
             <md-input-container class="md-block md-flex"
                                 ng-repeat="note in editor.card.notes">
diff --git a/UI/Templates/ContactsUI/UIxContactViewTemplate.wox b/UI/Templates/ContactsUI/UIxContactViewTemplate.wox
index baf79a1c2..b144d0a6b 100644
--- a/UI/Templates/ContactsUI/UIxContactViewTemplate.wox
+++ b/UI/Templates/ContactsUI/UIxContactViewTemplate.wox
@@ -146,6 +146,33 @@
               </div>
             </div>
 
+	    <div class="section" ng-show="editor.card.customFields">
+              <div class="pseudo-input-container" ng-show="editor.card.customFields['1']">
+                <label class="pseudo-input-label"><var:string label:value="Custom 1"/></label>
+		<div class="pseudo-input-field">
+                  <span>{{editor.card.customFields['1']}}</span>
+		</div>
+              </div>
+	      <div class="pseudo-input-container" ng-show="editor.card.customFields['2']">
+                <label class="pseudo-input-label"><var:string label:value="Custom 2"/></label>
+		<div class="pseudo-input-field">
+                  <span>{{editor.card.customFields['2']}}</span>
+		</div>
+              </div>
+	      <div class="pseudo-input-container" ng-show="editor.card.customFields['3']">
+                <label class="pseudo-input-label"><var:string label:value="Custom 3"/></label>
+		<div class="pseudo-input-field">
+                  <span>{{editor.card.customFields['3']}}</span>
+		</div>
+              </div>
+	      <div class="pseudo-input-container" ng-show="editor.card.customFields['4']">
+                <label class="pseudo-input-label"><var:string label:value="Custom 4"/></label>
+		<div class="pseudo-input-field">
+                  <span>{{editor.card.customFields['4']}}</span>
+		</div>
+              </div>
+            </div>
+
             <div class="section" ng-show="editor.card.notes[0].value.length">
               <div class="pseudo-input-container" ng-repeat="note in editor.card.notes">
                 <label class="pseudo-input-label"><var:string label:value="Note"/></label>
diff --git a/UI/WebServerResources/js/Contacts/CardController.js b/UI/WebServerResources/js/Contacts/CardController.js
index 495b0e3fa..81a6046a6 100644
--- a/UI/WebServerResources/js/Contacts/CardController.js
+++ b/UI/WebServerResources/js/Contacts/CardController.js
@@ -29,6 +29,9 @@
     vm.addPhone = addPhone;
     vm.addUrl = addUrl;
     vm.addAddress = addAddress;
+    vm.canAddCustomField = canAddCustomField;
+    vm.addCustomField = addCustomField;
+    vm.deleteCustomField = deleteCustomField;
     vm.userFilter = userFilter;
     vm.save = save;
     vm.close = close;
@@ -98,6 +101,20 @@
       var i = vm.card.$addUrl('', '');
       focus('url_' + i);
     }
+    function canAddCustomField() {
+      return _.keys(stateCard.customFields).length < 4;
+    }
+    function addCustomField() {
+      if (!angular.isDefined(vm.card.customFields))
+        vm.card.customFields = {};
+
+      // Find the first 'available' custom field
+      var availableKeys = _.pullAll(['1', '2', '3', '4'], _.keys(stateCard.customFields));
+      vm.card.customFields[availableKeys[0]] = "";
+    }
+    function deleteCustomField(key) {
+      delete vm.card.customFields[key];
+    }
     function addAddress() {
       var i = vm.card.$addAddress('', '', '', '', '', '', '', '');
       focus('address_' + i);