Two Free E-mail Deliverability Tools
Jeanne Jennings has a great article over at ClickZ on 2 free email deliverability tools that people should be leveraging.
I can say that I have and will continue to leverage both of these. Both Return Path and EDS are top notch at what they do and these free tools are the tip of the iceberg.
My suggestion is that you look at both of these tools if you are concerned with deliverability and then really explore their other offerings to see the fit in your organization.
The link to the post is below.