Key takeaways
- Sender reputation is a provider's judgment of your domain and IP, based on how recipients react and how clean your sending is.
- Complaints, bounces, spam trap hits and engagement are the main inputs.
- Domain reputation now matters as much as IP reputation, and it follows you across providers.
- Check Postmaster Tools, Microsoft SNDS, blocklists and your own engagement by provider.
- Recovery takes weeks: send less, send only to engaged contacts, and fix list quality first.
In this guide
- What sender reputation is
- Domain reputation vs IP reputation
- What builds or damages reputation
- How to check your reputation
- Signs your reputation is slipping
- A 30-day plan to rebuild a damaged reputation
- Reputation myths
- Reputation by mailbox provider: what each one weighs
- Reputation and engagement: the feedback loop
- Reputation for transactional mail
- Reputation checklist by role
- Reputation and list size
- Frequency and reputation
- The habits that protect reputation long term
- Frequently asked questions
What sender reputation is
Sender reputation is the opinion each mailbox provider forms about you as a sender, based on your past behavior. Gmail, Microsoft, Yahoo and business security filters all keep their own version. They use it to decide whether your next email goes to the inbox, to spam, or is rejected.
You cannot see the score itself, and there is no single universal number. But the inputs are well known, and you can measure most of them.
Domain reputation vs IP reputation
| IP reputation | Domain reputation | |
|---|---|---|
| Attached to | The IP address of the sending server | Your authenticated domain (From and DKIM) |
| On shared platforms | Shared with other senders, managed by the provider | Yours alone |
| Changes when you switch platform | Yes | No, it follows you |
| Importance today | Still used | Increasingly central |
Because providers rely more and more on domain reputation, the domain you authenticate with is your long-term asset. That is also why changing platforms or IPs rarely fixes a reputation problem; see dedicated vs shared IP.
What builds or damages reputation
| Factor | Builds reputation | Damages reputation |
|---|---|---|
| Spam complaints | Below 0.1% | Above 0.1%, critical above 0.3% |
| Bounces | Under 2% total | High hard bounces from old or unverified lists |
| Spam traps | None | Any hits, especially pristine traps |
| Engagement | Opens, clicks, replies, "not spam" actions | Deletes without reading, long-term inactivity |
| Authentication | SPF, DKIM, DMARC aligned | Failures, missing records |
| Consistency | Regular volume and schedule | Sudden spikes after long silences |
| Blocklists | Not listed | Listed on major lists |
How to check your reputation
Gmail
Google Postmaster Tools shows your spam rate, authentication results, compliance with sender requirements and delivery errors. Google is retiring the old reputation charts, but the spam rate and compliance views are the signals that matter most anyway.
Microsoft
Microsoft's SNDS (Smart Network Data Services) shows data for IPs you control, mainly useful with a dedicated IP. For everyone, watch delivery and junk placement to Outlook.com and Hotmail; see Outlook-specific fixes.
Blocklists
Check major blocklists monthly and after any sudden drop. See how to check blocklists.
Your own data
Your email platform's reports are the most practical source: complaints, bounces and clicks per campaign, and ideally per mailbox provider. A drop in clicks at one provider only is often the first sign of reputation trouble there.
Seed tests
An inbox placement test shows where a campaign lands at each provider. It is a snapshot, but useful to confirm a suspicion.
Signs your reputation is slipping
- Clicks fall at one provider while others stay stable
- Spam rate in Postmaster Tools climbs above 0.1%
- More deferrals ("try again later") and rate-limit errors
- Seed tests show spam placement at one or more providers
- Policy bounces mentioning reputation or blocklists
A 30-day plan to rebuild a damaged reputation
Week 1: Stop the damage
- Pause sends to old, imported and unengaged segments.
- Check authentication: SPF, DKIM and DMARC aligned for every stream. See SPF, DKIM and DMARC explained.
- Find the event that started the decline: an import, a new list source, a frequency change, a big promotion.
Week 2: Clean and focus
- Verify the list and remove invalid, disposable and risky addresses.
- Build an "engaged" segment: clicked, replied or purchased in the last 60 to 90 days.
- Send only to that segment, with your most useful, expected content.
Week 3: Rebuild positive signals
- Keep a steady, moderate frequency.
- Encourage replies and make unsubscribing effortless.
- Run a re-engagement step for inactive contacts before removing them.
Week 4: Widen carefully
- Gradually add less recently engaged segments, as in a warm-up.
- Stop widening as soon as complaints or bounces rise.
Serious damage can take longer than a month. The direction matters: steady, clean sending to people who want your emails always moves reputation upward.
Reputation myths
- "A new domain will reset everything." Providers connect new domains to old behavior, and the cause moves with you.
- "Sending more will improve reputation." Volume without engagement makes things worse.
- "Spam words killed my reputation." Content plays a small role compared with complaints, bounces and engagement.
- "Reputation is the same everywhere." Each provider has its own view. You can be fine at Gmail and struggling at Microsoft.
Reputation by mailbox provider: what each one weighs
| Provider | Signals that weigh heavily | Where you see it |
|---|---|---|
| Gmail | User spam reports, authentication, engagement, compliance with sender rules | Postmaster Tools, clicks from Gmail users |
| Microsoft | Junk clicks, sending history, IP data, authentication | Delivery to Outlook.com, SNDS for dedicated IPs |
| Yahoo / AOL | Complaints through the feedback loop, authentication | Complaint reports in your platform |
| Business security gateways | Domain age, blocklists, link reputation, content | Bounces and quarantine reports from B2B contacts |
This is why a single global score does not exist. Diagnose provider by provider, and fix the provider where results dropped first.
Reputation and engagement: the feedback loop
Reputation and engagement feed each other. Good reputation puts your emails in the inbox, where people can open and click them. Engagement then improves reputation further. The reverse is also true: emails in spam get no engagement, which lowers reputation, which sends more emails to spam.
Breaking a negative loop always starts with the same move: send less, to fewer people, who really want your emails. It feels counterintuitive, but it is the fastest way to reverse the trend. Once engagement rises, widen the audience step by step.
Reputation for transactional mail
Receipts and password resets usually get excellent engagement, so their reputation is naturally strong. Protect it by keeping them on a separate stream from marketing, ideally a different subdomain, and by not adding heavy promotions to them. If marketing reputation drops, customers still receive what they need. See sending from a subdomain.
Reputation checklist by role
| Role | Responsibility |
|---|---|
| Marketing | Consent, targeting, frequency, content, complaint rate |
| Data / CRM owner | List sources, verification, sunset policy, suppression lists |
| IT or agency | SPF, DKIM, DMARC, DNS changes, new tool authentication |
| Management | Refusing purchased lists and unrealistic volume targets |
Reputation problems often appear when these roles do not talk to each other: marketing imports a list that the data owner never checked, or IT changes DNS without telling marketing. A short monthly review with all three solves most of them.
Reputation and list size
A smaller, engaged list almost always has a better reputation than a large, tired one, and it reaches more real readers in practice. When reviewing results, judge the program by clicks, replies and revenue, not by the number of contacts. That mindset makes good reputation decisions, such as removing inactive contacts, much easier to accept.
Frequency and reputation
Sending too often is one of the quietest reputation killers. Each extra email gives tired subscribers another chance to complain or ignore you. If complaints rise when you increase frequency, the audience is telling you something. Offer a lower-frequency option in a preference center, and send the highest frequency only to your most engaged segment. Reputation improves without losing your best readers.
The habits that protect reputation long term
- Permission-based list building only
- Verification at signup and before sending to old data
- Sunset policy for long-inactive contacts
- Complaints under 0.1%, bounces under 2%
- Consistent sending rhythm
- Authentication checked whenever a new tool is added
Most reputation problems I diagnose are list problems in disguise. Start with your bounce rate and spam trap risk, and the rest becomes much easier.
Frequently asked questions
What is a good sender reputation?
There is no universal score. In practice, a good reputation means low complaint rates (below 0.1%), low bounces (below 2%), no blocklist listings and stable inbox placement.
Can I see my exact reputation score?
No. Mailbox providers do not share their internal scores. You see indicators instead: spam rate, delivery errors, blocklists, and engagement trends.
Does a new domain have a bad reputation?
A new domain has no reputation, which is treated with caution. It needs a gradual warm-up to earn trust.
Does changing my domain fix a bad reputation?
Only briefly, and providers can link the new domain to the old behavior. Fix the cause instead; otherwise the new domain will be damaged too.
How long does it take to improve sender reputation?
Usually several weeks of consistent, clean sending. Serious damage, such as a Spamhaus listing, can take longer.
