Refusing or failing to pursue action against a violation of a trademark can cause a trademark to be considered abandoned and therefore invalid. It is a genuine legal concern. This is supposed to prevent individuals and companies from “sitting” on a trademark without the intention of using it.
So you are saying that you think that "Postman" declining to pursue legal action against "Postwoman" might lead to a court deciding that "Postman" is a generic mark - do I have that correct?
Can you point to a case even vaguely close to this fact pattern?
>So you are saying that you think that "Postman" declining to pursue legal action against "Postwoman" might lead to a court deciding that "Postman" is a generic mark
Per this posting from a law firm [1], as your question is stated with the inclusion of "might" the answer is yes. Apparently it can go one of three ways: abandoning, not impacting/abandoning, or diminishing. Two of these results are bad for the trademark holder.
I'd assume a C&D letter would be sufficient to get a proper result or at least should be the first move in these matters, but I'm not a lawyer nor play one on TV or online.
You don't necessarily need to sue competitors for being misleading, but you do generally have to show you are trying to defend your trademarks and a lawsuit is a nice expensive papertrail.
I assert that literally zero of these cases are even close to this one in terms of the degree of abandonment represented by failure to take action against Postwoman.
Can you specify a single one that you think is similar?
You could have made a simple search and found more confirmation than I could possibly provide. Even the USPTO has top-level search results to that effect.