Case Study: City of Napa achieves rapid DMARC enforcement and phishing protection with Valimail

City of Napa defeats phishing with complete email identity solution

The City of Napa, a municipal government serving over 76,000 residents, relies on email as its primary communication channel across many departments and field staff. Its IT team needed to stop domain spoofing and rising phishing attacks without disrupting legitimate mail, reduce staff workload, and integrate with the city’s existing Microsoft 365 environment while achieving DMARC enforcement.

After evaluating Valimail’s DMARC Monitor, the city deployed Valimail Enforce and Valimail Defend to add a zero‑trust sender identity layer that integrates with Microsoft 365 and Office ATP. Valimail’s analysis exposed spoofed and misauthenticated senders, enabled DMARC p=reject in five days, authenticated 47,000 messages, blocked hundreds of suspicious emails, and protected hundreds of mailboxes—resulting in cleaner inboxes and reclaimed IT time.

City of Napa

Garrett Brown

Network Systems Administrator