Proof is always a problem in "negative reference" situations. A prior writer has suggested using a "reference check" company which is actually a very common suggestion I make when faced with these types of issues. Might I suggest that you not limit your inquiry to just that one issue but that if you do hire a reference check company that you invest in one that has you execute authorizations for release of information just as many employers require of candidates so you can learn a little more about who is saying what before you submit your next set of applications. As proof is your issue this is more of a "private investigator" type of a question right now and you may want to search websites similar to this one for private investigators for better answers and ideas. Good luck.
Difficult situation, and not one that lends itself to a legal solution. You do not presently have a lawsuit or claim against anyone based on the facts you have summarized here.
But there may be some productive efforts to be made. There are firms that will, for a fee, conduct "reference checks" to determine whether a former employer is causing employment problems. There may be a variation of such services that could be applied to your circumstances in order to determine whether your suspicion's are correct. Use the internet to locate reputable and professional firm and discuss customizing the service for your needs.
Unless your final email was truly abusive and intemperate, it seems unlikely that your suspicions are correct. The provocation you cite is too modest for all this retaliatory activity, in my view.
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I agree with Ms. McCall. First, to blacklist somebody would require that the company recruiter devote incredible resources to you, and I'm guessing that s/he has enough other work to make that difficult. Second, you probably would not list this company that did not hire you on your own documents. It seems more likely that there is something in your cover letter, your resume, or your telephone demeanor that is distancing you from opportunity. It may be time to hire a professional headhunter or career specialist to give you an appraisal of how your entire employment package is presented. In fact, for people who sincerely believe that there is some former employer that is giving very poor references when potential employers call, there is also very little concrete relief. A Washington statute provides immunity to former employers for honest assessments and opinions during reference checks. It would be best to focus on the one thing that you can contol -- your own resume, cover letter, and interview skills package.
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