diff --git a/addons/mass_mailing/static/src/js/mass_mailing_widget.js b/addons/mass_mailing/static/src/js/mass_mailing_widget.js
index d8000b201eb..9312ffc3053 100644
--- a/addons/mass_mailing/static/src/js/mass_mailing_widget.js
+++ b/addons/mass_mailing/static/src/js/mass_mailing_widget.js
@@ -72,26 +72,7 @@ var MassMailingFieldHtml = FieldHtml.extend({
             self._isDirty = self.wysiwyg.isDirty();
             self._doAction();
 
-            // fix outlook image rendering bug (this change will be kept in both
-            // fields)
-            _.each(['width', 'height'], function (attribute) {
-                $editable.find('img').attr(attribute, function () {
-                    return $(this)[attribute]();
-                }).css(attribute, function () {
-                    return $(this).get(0).style[attribute] || attribute === 'width' ? $(this)[attribute]() + 'px' : '';
-                });
-            });
-
-            convertInline.attachmentThumbnailToLinkImg($editable);
-            convertInline.fontToImg($editable);
-            convertInline.classToStyle($editable, self.cssRules);
-            convertInline.bootstrapToTable($editable);
-            convertInline.cardToTable($editable);
-            convertInline.listGroupToTable($editable);
-            convertInline.addTables($editable);
-            convertInline.formatTables($editable);
-            convertInline.normalizeColors($editable);
-            convertInline.normalizeRem($editable);
+            convertInline.toInline($editable, self.cssRules);
 
             self.trigger_up('field_changed', {
                 dataPointID: self.dataPointID,
diff --git a/addons/web_editor/static/src/js/backend/convert_inline.js b/addons/web_editor/static/src/js/backend/convert_inline.js
index 9104c2107d3..92ed8ec23a9 100644
--- a/addons/web_editor/static/src/js/backend/convert_inline.js
+++ b/addons/web_editor/static/src/js/backend/convert_inline.js
@@ -323,6 +323,42 @@ function classToStyle($editable, cssRules) {
         }
     });
 }
+/**
+ * Convert the contents of an editable area (as a JQuery element) into content
+ * that is widely compatible with email clients. If no CSS Rules are given, they
+ * will be computed for the editable element's owner document.
+ *
+ * @param {JQuery} $editable
+ * @param {Object[]} [cssRules] Array<{selector: string;
+ *                                   style: {[styleName]: string};
+ *                                   specificity: number;}>
+ */
+function toInline($editable, cssRules) {
+    if (!cssRules) {
+        cssRules = getCSSRules($editable[0].ownerDocument);
+    }
+
+    // Fix outlook image rendering bug (this change will be kept in both
+    // fields).
+    _.each(['width', 'height'], function (attribute) {
+        $editable.find('img').attr(attribute, function () {
+            return $(this)[attribute]();
+        }).css(attribute, function () {
+            return $(this).get(0).style[attribute] || attribute === 'width' ? $(this)[attribute]() + 'px' : '';
+        });
+    });
+
+    attachmentThumbnailToLinkImg($editable);
+    fontToImg($editable);
+    classToStyle($editable, cssRules);
+    bootstrapToTable($editable);
+    cardToTable($editable);
+    listGroupToTable($editable);
+    addTables($editable);
+    formatTables($editable);
+    normalizeColors($editable);
+    normalizeRem($editable);
+}
 /**
  * Convert font icons to images.
  *
@@ -953,25 +989,7 @@ FieldHtml.include({
         $odooEditor.removeClass('odoo-editor');
         $editable.html(html);
 
-        attachmentThumbnailToLinkImg($editable);
-        fontToImg($editable);
-        classToStyle($editable, this.cssRules);
-        bootstrapToTable($editable);
-        cardToTable($editable);
-        listGroupToTable($editable);
-        addTables($editable);
-        formatTables($editable);
-        normalizeColors($editable);
-        normalizeRem($editable);
-
-        // fix outlook image rendering bug
-        _.each(['width', 'height'], function(attribute) {
-            $editable.find('img').attr(attribute, function(){
-                return $(this)[attribute]();
-            }).css(attribute, function(){
-                return $(this).get(0).style[attribute] || attribute === 'width' ? $(this)[attribute]() + 'px' : '';
-            });
-        });
+        toInline($editable, this.cssRules);
         $odooEditor.addClass('odoo-editor');
 
         this.wysiwyg.setValue($editable.html(), {