diff --git a/app/assets/javascripts/app/lib/app_post/utils.coffee b/app/assets/javascripts/app/lib/app_post/utils.coffee
index 4efc203b1..5a80d973c 100644
--- a/app/assets/javascripts/app/lib/app_post/utils.coffee
+++ b/app/assets/javascripts/app/lib/app_post/utils.coffee
@@ -1205,9 +1205,12 @@ class App.Utils
 
     html.find('img').each( (index) ->
       src = $(@).attr('src')
-      if !src.match(/^(data|cid):/i) # <img src="cid: ..."> may mean broken emails (see issue #2305)
-        base64 = App.Utils._htmlImage2DataUrl(@)
-        $(@).attr('src', base64)
+
+      # <img src="cid: ..."> or an empty src attribute may mean broken emails (see issue #2305 / #2701)
+      return if !src? or src.match(/^(data|cid):/i)
+
+      base64 = App.Utils._htmlImage2DataUrl(@)
+      $(@).attr('src', base64)
     )
     html.get(0).innerHTML
 
diff --git a/public/assets/tests/html_utils.js b/public/assets/tests/html_utils.js
index 36edadca4..a409a1674 100644
--- a/public/assets/tests/html_utils.js
+++ b/public/assets/tests/html_utils.js
@@ -3167,11 +3167,18 @@ test("htmlImage2DataUrl", function() {
   result = App.Utils.htmlImage2DataUrl(source)
   equal(result, should, source)
 
+  // GitHub issue #2305
   source = '<img src="cid:1234">some test'
   should = '<img src="cid:1234">some test'
   result = App.Utils.htmlImage2DataUrl(source)
   equal(result, should, source)
 
+  // GitHub issue #2701
+  source = '<img alt="foo">some test'
+  should = '<img alt="foo">some test'
+  result = App.Utils.htmlImage2DataUrl(source)
+  equal(result, should, source)
+
 });
 
 test('App.Utils.icon()', function() {