diff --git a/openerp/tools/mail.py b/openerp/tools/mail.py
index a54f99ba1ad..9df7499d0c8 100644
--- a/openerp/tools/mail.py
+++ b/openerp/tools/mail.py
@@ -130,11 +130,15 @@ def html_email_clean(html):
         dest += source[idx:]
         return dest
 
-    if not html:
+    if not html or not isinstance(html, basestring):
         return html
 
     html = ustr(html)
 
+    # 0. remove doctype and xml tags
+    doctype = re.compile(r"(<[?]xml.*?[?]>|<[!]DOCTYPE.*?>)[\n\r\s]*", re.IGNORECASE | re.DOTALL)
+    html = doctype.sub(r"", html)
+
     # 1. <br[ /]> -> \n, because otherwise the tree is obfuscated
     br_tags = re.compile(r'([<]\s*[bB][rR]\s*\/?[>])')
     html = _replace_matching_regex(br_tags, html, '__BR_TAG__')