Building sender reputation
How to build and maintain a strong sender reputation so your emails reach the inbox.
Sender reputation is a score that inbox providers (Gmail, Outlook, Yahoo, etc.) assign to your sending domain and IP. A good reputation means inbox placement. A bad one means spam folder — or worse, outright rejection.
What affects reputation
- Bounce rate — hard bounces signal you're sending to bad addresses. Keep below 5%.
- Complaint rate — when recipients mark your email as spam. Keep below 0.1%.
- Engagement — opens and clicks signal wanted email. Low engagement hurts reputation.
- Sending volume patterns — sudden spikes look suspicious. Consistent, gradual growth looks legitimate.
- Spam trap hits — sending to recycled or planted spam trap addresses is catastrophic.
Warming up a new domain
If you're sending from a brand new domain (or one that hasn't sent email recently), you need to warm it up gradually:
Week 1
Send to your most engaged contacts — people who have recently opened or clicked your emails. Start with 100-500 per day.
Week 2
Increase to 1,000-2,000 per day. Continue targeting engaged contacts.
Week 3
Expand to 5,000+ per day and begin including less-engaged segments.
Week 4+
Scale to your full volume. Monitor bounce and complaint rates throughout.
Never send your entire list on day one from a new domain. Inbox providers will throttle or block you.
Monitoring reputation
- AWS SES dashboard — shows bounce rate, complaint rate, and sending quotas
- Google Postmaster Tools — the best insight into how Gmail views your domain
- Sendra campaign reports — track per-campaign engagement trends
Recovering from poor reputation
If your reputation has dropped:
- Stop sending to disengaged contacts
- Clean your list — remove bounces, complainers, and contacts inactive for 90+ days
- Send only to engaged contacts for 2-4 weeks
- Monitor metrics closely — bounce and complaint rates should drop
- Gradually re-expand your audience