How can one discern whether a copyright infringement notice is legitimate (for using a picture in public domain)?
A start-up non-profit advocated/educated about the current reality of some devastating natural disasters globally, getting almost no media coverage thus relief agencies struggle and ask for donation-help to pay for their life-saving and recovery work. In recent years were back-to-back major cyclones in southeast Africa that proved this problem. A headline about relief agencies asking for donations was cropped and posted on a non-profit's new website, accompanied by a picture showing citizens in that nation after the destruction. Sometime in early 2018, an email (in my spam folder) asserted copyright infringement thus the picture was immediately removed. Nothing was heard again so the matter seemed long over.
In recent days a similar claim via email was received, again with an old screenshot of the non-profit's former website (one had to scroll down an obscure page on the virtually unknown incorporated non-profit's website to see the image). The website was shut down by the host in September 2018 when subscription expired. A redesigned version of site (without the picture) went live about 2 weeks ago. The 'threat' was to be taken to court and held to a 6-figure penalty plus legal expenses... or agree to settle immediately for less than $2K. The Fair Use doctrine was asserted by the non-profit (which has no revenue, no bank account, no employees, and no officers... just volunteers mainly on standby). The contact claiming to represent the copyright holder responded that the non-profits interpretation of Fair Use was wrong. The non-profit's founder revealed financial hardship due to long term unemployment. The same contact then said to apply for hardship by providing personal financial info (last 2 tax filings and 6 months of bank statements) after being told the non-profit is incorporated. The non-profit's advocacy for a commitment to deploy donation enabling initiatives in the immediate aftermath of any major natural disaster anywhere will not yield and fee or commission or economic benefit to the non-profit nor the founder. This is pure advocacy to do better for the greater good when lives are at stake anywhere globally.