'Rule of Thumb' for Addressing Cover Letters?

Dear Experts, I was wondering what I should do if I do not have a specific person to refer to with my cover letter. Should I call the organization and ask them about the hiring manager? Or I heard that writing "Dear Prospective Employer" is a good way to work past this issue. Our Twitter Advice Project (T.A.P.) is no longer an active campaign. To find an answer to the above question, please use the "Search" box in the right-hand column of this website.

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