Okay, gotta ask for learning purposes: what's a NACK email? *EDIT: Ah. "Negative acknowledgement." In other words, someone hears from them regardless of wheth

Okay, gotta ask for learning purposes: what's a NACK email? *EDIT: Ah. "Negative acknowledgement." In other words, someone hears from them regardless of whether they're impacted or not, i.e. [NOT IMPACTED].