I’ve been using Mail w Attachments (which from memory was written by Dave) successfully for years, most recently in Yosemite, but it has stopped working in Sierra. ( I’m using Sierra only because I had to get a new MacBook Pro.) The emails are sent, but without the attachments. There is no error message.
I’m using OSX10.12.4 but I don’t think it worked in 10.12.2 either. Has anybody been able to send attachments successfully in Sierra?