There is a good reason for there to be many companies that are making money providing this service, it is not something that is easily fixable through a one time consultancy.
I would suggest you either hire a person that does deliverability or you use one of the existing companies. It took them all several years to get it right and constant maintenance. Spam evolves, anti spam evolves, commercial email must evolve to keep from being the former in the eyes of the latter.
As an email admin the first thing I did when Amazon announced the service is to block those IPs also at my smtp gateway (I normally block all aws IPs among many others).
On Wed, Feb 27, 2013 at 3:04 PM, Varun Bihani <[address removed]>
Stultorum infinitus est numerus
Pedo mellon a minno