If you look at the Help for the email node you will see:
If the payload is a binary buffer then it will be converted to an attachment. The filename should be set using
msg.filename. Optionallymsg.descriptioncan be added for the body text.Alternatively you may provide
msg.attachmentswhich should contain an array of one or more attachments in nodemailer format. believe the problem is that you have msg.filename and msg.attachments.
Follow the link to see how msg.attachment needs to be setup.