Definition
Your sending reputation is the score receiving ISPs assign to your domain and IP address based on your email history. It is the single biggest factor in whether your email reaches the inbox, lands in spam, or gets blocked. Every major provider — Gmail, Outlook, Yahoo — calculates reputation differently, but they weigh the same core signals.
Reputation lives in two places: your IP address (shared or dedicated) and your sending domain. Domain reputation has become more important because shared IPs blur the reputation of many senders. A poor reputation is self-reinforcing: fewer inbox deliveries means lower engagement, which lowers reputation further.
Key Reputation Signals
| Signal | Healthy Threshold |
|---|---|
| Spam complaint rate | Below 0.1% |
| Hard bounce rate | Below 2% |
| Open rate | Above 15-20% |
| Click rate | Above 1-2% |
| Authentication (SPF/DKIM/DMARC) | Fully configured |
| Sending volume | Consistent, not erratic |
What Damages Sending Reputation
- High complaint rates — recipients marking your mail as spam
- High bounce rates — sending to invalid or stale addresses
- Low engagement — large blocks of unopened, unclicked mail
- Authentication failures — SPF, DKIM or DMARC misconfiguration
- Erratic volume — sudden spikes or gaps in sending activity
- Purchased lists — cold contacts who never opted in
How to Monitor Sending Reputation
- Google Postmaster Tools — Gmail-specific delivery and reputation data
- Microsoft SNDS — Outlook.com and Hotmail reputation data
- Sender Score (Validity) — a 0-100 third-party reputation score
- Your ESP's reputation dashboard — often includes ISP-specific breakdowns
- DMARC aggregate reports — show authentication and delivery patterns
How to Recover a Damaged Reputation
- Identify the cause — complaints, bounces, or authentication failures
- Fix authentication — confirm SPF, DKIM and DMARC pass for every sender
- Clean the list — remove invalid addresses and unengaged contacts
- Reduce volume temporarily — send to your most engaged segment first
- Rebuild gradually — scale volume up as engagement recovers
- Monitor weekly — watch complaint and bounce rates as you recover
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Frequently Asked Questions
Third-party scores like Sender Score range from 0 to 100, with 80+ generally considered good and 90+ excellent. However, ISPs do not use a single public score, so your own engagement and complaint metrics are the most reliable indicators.
A new domain or IP typically needs 4-8 weeks of consistent, well-authenticated sending to build reputation. Repairing a damaged reputation can take longer — often several months of clean, engaged sending before delivery fully recovers.
Increasingly, yes. Shared IPs blur individual senders' reputation, so ISPs weight the sending domain and its authentication history heavily. A strong domain reputation helps even when the IP changes.
Very fast. A single high-complaint or high-bounce campaign can depress delivery within days. Reputation is quick to damage and slow to rebuild, which is why list hygiene and engagement monitoring matter more than any single send.