When was this email sent:
"To my understanding your contract was never fully executed. The client decided to not fill the position at the last minute and we will not be requiring your services at this time. You will not be receiving any compensation from Optimal. Your resume and information will be kept on file, and if a position becomes available we will reach out to you. Please let me know if you have any other questions. Thank you. "
Also, something else to think about, the contract itself states that "the terms included in this agreement (including but not limited to assignment duration, bill rates, etc) are defined by customer requirements and may change on short notice." Additionally, the contract provides that "this Agreement may be terminated by Optimal, at will
, at any time, with or without cause, upon termination
of the work statement or contract with Optimal's end client." In this case, they could say the contract with the end client terminated and thus they were allowed to terminate your contract immediately pursuant to the terms.
If they were allowed to so terminate the agreement, then they can say you were not damaged.
Your counter-argument would be that they have repudiated the agreement and cannot stand on that term to defend them from the damages that they caused.