Free Sender Reputation Checker
Combines multiple signals into a single reputation assessment.
What Sender Reputation Is
Sender reputation is not a single number stored in one place. Email providers maintain internal assessments of sending domains and IP addresses based on observed behavior over time. Those assessments are not published, but their effects are visible: domains with strong reputation consistently land in the inbox, and domains with weak or damaged reputation see elevated spam placement rates, throttling, or outright rejection.
Two distinct reputations affect your deliverability and the checker evaluates signals relevant to both. Domain reputation is tied to your sending domain — the part after the @ in your from address. Gmail, Outlook, Yahoo, and other providers track how recipients engage with mail from your domain. High open and reply rates signal that recipients find your messages worth reading. High spam complaint rates, hard bounces, and low engagement signal the opposite. Domain reputation accumulates over time and is harder to damage quickly than IP reputation, but also slower to rebuild once it is damaged.
IP reputation is tied to the sending IP address that actually transmits your email. If you send through a platform that uses shared IP pools, your IP reputation is partially a function of other senders on the same pool. If another sender on your shared IP generates high complaint rates, your delivery suffers even if your own sending behavior is clean. Sending through your own accounts — Google Workspace, Microsoft 365, AWS SES — gives you isolated IP reputation tied only to your own activity.
The signals that affect reputation most are: spam complaint rate (the primary driver at every major provider), hard bounce rate, spam trap hits, authentication pass rate, sending volume consistency, domain age, and recipient engagement patterns including opens, replies, and unsubscribes. Most of these are behavioral signals accumulated over time, not configuration items you set once.
How to Read Your Reputation Check Results
The checker surfaces signals that are publicly visible and queryable: DNS authentication status, blacklist presence, domain age, and configuration completeness. Each signal has a clean state and a flagged state.
Authentication signals show each of SPF, DKIM, and DMARC as passing or failing. Passing means the record exists, resolves correctly, and is properly configured. Failing means one of those conditions is not met. A record that exists but has configuration errors — an SPF record with 11 DNS lookups, a DKIM record with an invalid key format — shows as failing even though the record is technically present. Failing authentication is not a soft negative. It is a direct signal to receiving servers that they cannot verify your mail.
Blacklist signals show whether your domain or sending IP appears on any major blacklist, which specific list, and the relative impact severity. A Spamhaus SBL listing is critical — it affects deliverability at the largest number of receiving servers and requires immediate action. A listing on a smaller, less-referenced list is lower priority but still worth resolving. Clean means no listings found across all queried databases. If the checker shows clean but your deliverability is still poor, the issue is likely in the behavioral signals the checker cannot see.
Domain age shows how long your domain has been registered. Domains under 30 days old are treated with elevated caution by receiving servers regardless of authentication status. This is not a problem you can solve quickly, only one you can account for with lower initial sending volumes and a proper warmup sequence. The overall assessment is a composite read across all signals — authentication failures and blacklist listings carry significantly more weight than domain age alone.
How to Improve a Damaged Reputation
Reputation recovery follows a specific sequence. Working steps out of order extends the timeline.
Fix authentication first. A failing SPF, missing DKIM signature, or absent DMARC record means every email you send is arriving without proper credentials. No warmup or list cleanup improves deliverability while authentication is broken. Fix SPF by correcting the record and keeping DNS lookups at 10 or under. Fix DKIM by publishing the correct selector records for each provider you send through. Set DMARC to at least p=none with a reporting address to begin receiving data on authentication failures. These changes propagate within 24 to 48 hours.
Remove blacklist listings next. Identify the specific list and follow their removal process. Spamhaus requires you to identify and fix the root cause before submitting a removal request — submitting without fixing the cause results in faster relisting. Barracuda has a self-service removal form that typically processes within 24 hours. SpamCop listings expire automatically within 24 to 48 hours once new spam reports stop coming in, so stopping the behavior that caused the listing is the fix. Do not begin volume recovery while you are still listed on a major blacklist.
Rebuild volume gradually once authentication passes and listings are cleared. Start at low daily volumes — 20 to 50 emails per day per sending account — and increase by 25 to 50 percent every 3 to 5 days as long as complaint rates stay under 0.1 percent and hard bounce rates stay under 2 percent. Expect 4 to 8 weeks to reach full operating volume from a damaged state. Attempting to accelerate this timeline by sending higher volumes too early typically triggers new flags and extends the recovery period.
Maintain list hygiene throughout. Remove hard bounces immediately after each campaign. Remove recipients who have not engaged in the past 90 days before ramping volume. A contact list full of cold or invalid addresses generates the bounce rates and spam trap hits that damaged your reputation in the first place. Cleaning the list before recovery sending prevents the same problem from recurring.
What Affects Reputation That a Checker Cannot See
The checker reads public signals. Reputation at the provider level is built from private behavioral signals the tool has no access to.
Engagement history is the most significant gap. Gmail and Outlook's inbox placement decisions are heavily weighted by how recipients on their platforms have historically engaged with your domain. A domain that has generated consistent opens and replies builds positive prior with each provider. A domain that has been consistently ignored, marked as spam, or heavily unsubscribed from builds the opposite. The checker shows you a public reputation snapshot — it does not show Gmail's or Outlook's internal domain score, which is the actual filter input.
Per-provider signals vary. Your reputation at Gmail is separate from your reputation at Outlook, Yahoo, and other providers. The same domain can have strong reputation at one provider and weak reputation at another based on different sending histories with each provider's user base. A public checker gives a unified view across publicly available signals, which masks the variation in how specific providers are treating your mail. If your deliverability problems are provider-specific, the cause is almost always in the behavioral history with that provider rather than in the public signals the checker evaluates.
Feedback loop data gives enrolled senders direct complaint rate information reported by providers like Yahoo and Microsoft through their FBL programs. This data is only available to senders who have enrolled in each provider's feedback loop and configured a complaint address in their DMARC record. If you are not enrolled, you have no visibility into your complaint rate — one of the most important signals driving your reputation. The checker cannot surface complaint rates you have not collected. Enrolling in major provider feedback loops is worth doing regardless of your current reputation status.