1 files changed, 3 insertions, 1 deletions
diff --git a/extensions/BMO/Extension.pm b/extensions/BMO/Extension.pm
index 94796ec72..1e24141b4 100644
--- a/extensions/BMO/Extension.pm
+++ b/extensions/BMO/Extension.pm
@@ -1127,7 +1127,9 @@ sub _inject_headers_into_body {
         # as_string() doesn't return the updated body for multi-part sub-parts.
         $email->parts_set([ $email->subparts ]);
     }
-    elsif ($email->content_type =~ /^text\/(?:html|plain)/) {
+    elsif (!$email->content_type
+           || $email->content_type =~ /^text\/(?:html|plain)/)
+    {
         # text-only email
         _replace_placeholder_in_part($email, $replacement);
     }