The new free Newsletter Plugin Composer themes don’t work properly for me, except Raw HTML. I save the e-mail messages to .eml file and open it with a text editor. I see they contain 2-3 Content-Transfer-Encoding fields. One or two Content-Transfer-Encoding: 8bit, and always Content-Transfer-Encoding: quoted-printable. This results in missing images, links and lost formatting except bold and italic.
I don’t know where this “quoted-printable” is coming from because my email encoding is set to 8 bit in Advanced Settings, Email encoding When I manually edit the file and replace “quoted-printable” with “8bit”, the eml file opens just fine in Outlook including all the images and links.
And I always have to send a test twice for newly created newsletter. No sending problem after that.
What is interesting is that all legacy themes work just fine for me.