The SolarWinds supply chain attack will likely prompt scores of compromised companies to send critical data breach notifications to their customers. But how many of these email notifications will go ignored, bounced or quarantined? Bulk emails sent en masse to recipients can easily appear suspicious, but they may actually be legally required alerts informing customers about data breaches, privacy policy changes or product recalls. Some may instruct recipients to change their passwords or subscribe to a credit monitoring service. Even customers who no longer use a particular company's services, or have unsubscribed from its marketing communications, or have set emails from that company as spam must still receive these so-called "mandatory" emails. And so it is imperative that senders follow guidelines that make their vital communications as secure and trustworthy as possible.