diff --git a/addons/mass_mailing/static/src/less/themes/theme_default.less b/addons/mass_mailing/static/src/less/themes/theme_default.less
index 74f71191db2..cfd1264e0c7 100644
--- a/addons/mass_mailing/static/src/less/themes/theme_default.less
+++ b/addons/mass_mailing/static/src/less/themes/theme_default.less
@@ -55,9 +55,12 @@
     background-color: @o_mm_def_color_alpha;
     padding: 24px 3%;
 
-    // Forces on <p/> elements as several mail clients does not correctly
-    // inherit font properties
+    // Forces on <p/> and <hx/> elements as several mail clients does not
+    // correctly inherit font properties
     &, p {
+        font-size: 14px; // force bootstrap default
+    }
+    &, p, h1, h2, h3, h4, h5, h6 {
         font-family: @o_mm_def_font;
         color: lighten(@o_mm_def_text_color, 20%);
     }
diff --git a/addons/web_editor/static/src/js/transcoder.js b/addons/web_editor/static/src/js/transcoder.js
index 05068972532..6b42e028b3a 100644
--- a/addons/web_editor/static/src/js/transcoder.js
+++ b/addons/web_editor/static/src/js/transcoder.js
@@ -121,6 +121,16 @@ var getMatchedCSSRules = function (a) {
         }
     });
 
+    // text-decoration rule is decomposed in -line, -color and -style. This is
+    // however not supported by many browser/mail clients and the editor does
+    // not allow to change -color and -style rule anyway
+    if (style['text-decoration-line']) {
+        style['text-decoration'] = style['text-decoration-line'];
+        delete style['text-decoration-line'];
+        delete style['text-decoration-color'];
+        delete style['text-decoration-style'];
+    }
+
     return style;
 };