"Dear Irene, dear Colleagues from Rainbow,
With reference to our previous e-mail exchanges and agreement that I would inform you if I find a job via other ways, I confirm that I've signed an indefinite contract with a private company, starting the 01/10/2018.
Despite the fact that I didn"t find this job with your intermediation, please allow me to thank you and your colleagues for the high level of dedication and commitment to your work, sending always almost "tailor made" offers to me, and for offering a very personal attention and empathy to my case. As matter of fact, - thought during my job research I was in contact with 9 "headhunter" companies -, with one exception you were the only ones treating my file in such a highly professional and nevertheless very personal manner, for which you will be the ones I will recomment to others in a similar situation.
I wish a lot of success to the whole team, and in case I would be again "on the hunt" you will be the first ones to be contacted!