How to detect subscribers ignoring their own preferences?

Here's a situation that sounds strange but is surprisingly common: a subscriber set a monthly preference but consistently opens every weekly send. Or they opted into "product updates only" but they're clicking on every promotional email too. Preferences and behavior have drifted, and you're sending based on a profile that no longer reflects reality.

The detection method is straightforward: cross-reference stated preferences against actual engagement data. If someone's stated preference is monthly but their open rate on weekly sends is consistently above your segment average, flag them for a preference refresh prompt. If someone opted into one content category but is regularly clicking links in other categories, that's a signal they'd benefit from broader opt-ins.

The right response is a prompt, not a silent override. Even if behavior suggests a subscriber would welcome more email or different content, sending beyond their stated consent is a risk under GDPR and similar frameworks, and it erodes the trust that preference centers are supposed to build. Instead, send a lightweight update email: "We noticed you've been opening our weekly sends, want to switch to weekly?" with a one-click confirmation. Anyone who clicks confirms the upgrade; anyone who doesn't remains on their stated preference.

Run this audit quarterly. Export your preference center data alongside engagement data from your ESP, match them at the contact level, and flag any subscriber where behavior and stated preferences have diverged significantly. Check the other direction too: subscribers who stated they want weekly emails but haven't opened anything in 60 days may need a re-engagement prompt or a frequency downgrade before you keep burning sends on an unresponsive contact.