Need way to bulk email

I need a way to mass email invoices instead of the one-at-a-time ability I have now. 

I use a factoring company to which I upload the Combined PDF through DropBox. However, I have a plant account manager who also needs a copy of the invoices, as her company's third-party payment processor doesn't send them out to the individual plants.  I know this is a them problem, but this company and their 3rd party payment processors' bureaucracies are on another level, and this is the far easier request.

I had been going back and emailing each one individually after the upload, but unfortunately, I miss a few.  It would just be easier if I could go back after invoicing all the loads and send them as one bulk email.