In 2024, Google and Microsoft introduced strict sender requirements. In 2025, they tightened them further. In 2026, the bar is higher than ever.
The new requirements
- SPF, DKIM, DMARC - All three must be properly configured. No exceptions.
- Unsubscribe header - Every cold email must include a one-click unsubscribe.
- Bounce rate under 2% - Email lists must be verified before sending.
- Complaint rate under 0.1% - If more than 1 in 1,000 recipients mark you as spam, your domain is burned.
What this means for founders
Volume-based cold email is dead. The founders who succeed in 2026 send fewer, better emails. 50 highly personalized emails per day beats 500 generic ones.
The tech setup
You need a separate domain for outreach (not your primary domain), properly warmed over 2-4 weeks. Use a dedicated IP if sending more than 100 emails per day. Monitor your domain reputation with Google Postmaster Tools.
Cluently handles the technical setup automatically. Domains are warmed gradually, reputation is monitored, and sending volume is adjusted based on deliverability signals.