Forwarding this bug from downstream.
Confirmed that it still exists in Evolution 2.7.92 and GtkHTML 3.11.92.
http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=201311


Description of problem:


Version-Release number of selected component (if applicable):
evolution-2.7.4-4

How reproducible:
always

Steps to Reproduce:
1. Launch firefox and open "www.redhat.com"
2. Select File -> Save Page As and save the web page (complete) to /root/Desktop
3. Launch Mail-Evolution and create a new Mail Message
4. In "Compose Message" window select Insert -> HTML File
5. Select the web page saved just now 
  
Actual results:
An error message pops up
------------
Error loading file '/root/Desktop/Red Hat | The Open Source
Leader': Invalid byte sequence in conversion input

------------


Expected results:


Additional info:
Web page "www.google.com" can be inserted successfully