In my point of view there is no tool but i am not confirmed. You can check it on Google. It provides you the best solution.
I use... two things.. Before I send any newsletters out, I send it to "mailtest@unlocktheinbox.com" and it will auto-respond and let me know if it's spammy. Secondly, Not as good as sending the email. They have an online tool you can use to run it through spam assassin here: unlocktheinbox.com/spamscore It considerably helped me reach more of my target audience.