Check out emailjs
After wasting lots of time on trying to make nodemailer work with large attachments, found emailjs and happy ever since.
It supports sending files by using normal File objects, and not huge Buffers as nodemailer requires. Means that you can link it to, f.e., formidable to pass the attachments from an html form to the mailer. It also supports queueing..
All in all, no idea why nodejitsu ppl chose nodemailer to base their version on, emailjs is just much more advanced.