I had some issues with email templates that contained UTF-8 characters during the base64 encoding in the previews. Encoding the HTML as UTF-8 before applying b64encode fixed the problem for me. What do you think about it? Let me know if there's more that need to be done for this to get considered for merging.
Encode HTML as UTF-8 before base64 encoding
0.5.2: Improve UTF-8 handling in previewer.
This improves the handling of non-ASCII encoded headers and message
bodies within the message previewer.
Thanks to @yunmanger1 and Sebastian Vetter (@elbaschid) for the initial
Closes #5, #6.
Resolved in 266f2ce, thanks!