Sender Reputation: How to Check IP & Domain reputation, Improve and Recover It

When a B2B team’s emails start landing in spam, the problem rarely stays with one rep. Each rep may work their own list from their own mailbox, but every mailbox sends from the same company domain. So one rep’s bad list, one rep doubling their volume in a week or one broken DNS record can change placement for everyone on the team.

Sender reputation is how mailbox providers judge whether mail from your domain, and the infrastructure behind it, is wanted. It’s built mainly from spam complaints, bounces, authentication and sending consistency, and each provider judges it separately on its own data. For most B2B teams sending from Google Workspace or Microsoft 365, the domain is the part of that reputation they actually control, because the IPs belong to the provider.

In this guide, we’ll cover what affects sender reputation and how to check it now that Gmail has dropped its reputation charts. We’ll then work through the practices that improve it, how to recover a domain that has slipped, and what poor reputation costs, so your team can treat email reputation management as a shared discipline rather than something one person fixes after the damage is done.

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Key takeaways

• Sender reputation is built mainly from complaints, bounces, authentication and consistency. Gmail asks senders to keep their spam rate below 0.10% and never reach 0.30%, and Yahoo sets its limit at 0.3%.
• Replies matter, opens don’t. Google states it doesn’t track open rates, so replies and complaints are the engagement signals that count.
• Gmail’s reputation charts are gone. The domain and IP reputation dashboards aren’t part of Postmaster Tools v2, so reputation now has to be read from spam rate, delivery errors, bounces and rejections.
• A team shares one reputation. On Google Workspace or Microsoft 365, the domain is the reputation the team controls, and one rep’s bad list affects every sender on it.
• Recovery follows a fixed order. Stop sending, find the cause, fix it, then resume slowly. Switching to a new domain without fixing the cause moves the problem rather than solving it.
• The cheapest protection happens before the send. Verify every list before it’s sent, stay within per-mailbox limits and keep SPF, DKIM and DMARC monitored.

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What Is Email Sender Reputation?

Email sender reputation is the trust mailbox providers attach to your sending domain and the infrastructure behind it, and it decides whether your mail reaches the inbox, lands in spam or gets rejected. There’s no single universal score. Each provider keeps its own: Gmail, for example, states that it “tracks volume, feedback, and limits per domain and IP address”, and Yahoo and Microsoft run their own assessments on their own data.

For a B2B team, that reputation is shared. Every rep sending from the company domain adds to it and draws on it, so one rep’s bad list or one broken DNS record can change placement for everyone. A credit score is a fair comparison, with one difference: there’s one account, and the whole team is borrowing against it.

Sender reputation covers both your domain and the IPs your mail leaves from. For how the two differ, and which one a team on Google Workspace or Microsoft 365 actually controls, see our comparison of IP reputation vs domain reputation.

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What Affects Your Sender Reputation Score?

Mailbox providers don’t publish their formulas, but they do publish the signals they act on. Six of them do most of the work. For a team sending from Google Workspace or Microsoft 365, all six are counted against the domain, because the IPs belong to the provider. Each rep sends from their own mailbox, but their complaints, bounces and volume all add to the same domain’s record.

Spam complaints

Complaints are the most direct signal a provider gets, and both Gmail and Yahoo publish a limit. Google’s sender guidelines ask senders to keep their spam rate below 0.10% and never reach 0.30%, and Yahoo’s sender best practices set the line at 0.3%. Both calculate the rate from mail that reached the inbox, so a handful of reports on a well-delivered send can move it quickly.

On a shared domain, complaints add up across the whole team. One rep running an aggressive sequence to a poorly targeted list can push the domain’s rate up for everyone, while the rest of the team sees placement fall without knowing why. Yahoo’s complaint feedback loop sends you reports of complaints from Yahoo users, which helps you trace a spike back to the sequence that caused it.

Bounces and list quality

Hard bounces tell a provider that a sender is mailing addresses it never confirmed. A hard bounce means the address doesn’t exist or will never accept mail; a soft bounce is temporary, such as a full mailbox or a server that’s briefly unavailable. Hard bounces are the ones that damage reputation, and on B2B lists they usually come from three places: bought lists, old CRM records, and contacts pulled from enrichment tools that guess at addresses.

The most damaging addresses are spam traps, which exist only to catch senders using stale or bought data. Catch-all addresses add a quieter risk. A basic check returns them as valid because the server accepts every address, so the bounce, if one comes, arrives later, often after the contact is already in a sequence. By then nobody connects it to the list that caused it.

Authentication and alignment

SPF, DKIM and DMARC prove the mail really comes from your domain, and providers now enforce them rather than just reward them. Gmail has required authentication from every sender since February 2024, with DMARC added for anyone sending more than 5,000 messages a day. Since May 5, 2025, Microsoft has rejected mail from senders of that volume to Outlook.com, Hotmail.com and Live.com that fails its SPF, DKIM and DMARC requirements, with the error 550 5.7.515.

Passing isn’t the same as aligning. Alignment means the domain in your From address matches the domain that SPF or DKIM authenticated, and DMARC checks for exactly that. Records usually break in routine ways: a new sending tool gets added without updating SPF or setting up DKIM, or the SPF record grows past the 10 DNS lookups the SPF standard allows, at which point SPF stops passing.

Sending volume and consistency

Providers trust patterns they recognize, and sudden changes look like the behavior of a compromised or spamming account. Google warns that “immediately doubling previously sent volumes suddenly could result in rate limiting or reputation drops.”

On a sales team, those spikes usually happen by accident. A new rep starts at full volume on day one, a new campaign launches across every mailbox at once, or every sequence is scheduled for Monday at 9 a.m. Each mailbox also has its own daily limit, covered in the best practices below.

Engagement

Replies are the clearest positive signal a B2B sender can earn. Opens are not part of it: Google states that it doesn’t track open rates. Beyond replies and spam reports, providers typically read engagement from what recipients do with a message, such as moving it out of spam or deleting it unread. Our guide to engagement-based filtering covers how that shapes placement.

Cold outreach starts at a disadvantage here, because recipients didn’t ask for the email. That makes targeting more important than copy: a message sent to the right person at the right company gets replies, and the same message sent to a broad list gets deleted, ignored or reported.

Content

Content matters less than the signals above, and mostly as a tiebreaker. Misleading subject lines, heavy link use and missing unsubscribe options all give filters a reason to doubt a message that the other signals haven’t already cleared.

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How to Check Your Domain Reputation Score

The tool most guides send you to no longer shows a reputation score. Google has excluded the domain and IP reputation dashboards from Postmaster Tools v2, and gave three reasons: reputation data “is not easily actionable for most senders”, changes in sender behavior are “slow to reflect”, and the dashboard “can be misleading as reputation is only one of many factors affecting deliverability.” At the time of writing, Google’s help page still describes the retirement of the legacy interface as postponed, but in August 2026 Mailgun reported that the reputation charts had already disappeared.

Gmail still scores your domain. You just have to read that score from the signals around it:

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For a quick check, work through three steps:

1. Open Postmaster Tools. Look at your spam rate, compliance status and any delivery errors citing low domain reputation.
2. Compare bounce rates by mailbox in your sending platform or sales engagement tool. A domain-wide problem shows up across every rep, while a list problem usually traces back to one or two.
3. Run an inbox placement test to see where your mail actually lands with Gmail and Outlook recipients.

If all three look healthy, your domain is likely in good standing. If one doesn’t, the practices below show where to start.

Read the spam rate with care. Google’s Postmaster Tools documentation states that the dashboard “reflects user-reported spam, not messages automatically marked as spam by Gmail,” and only counts mail delivered to engaged recipients’ inboxes. A low spam rate can therefore mean your mail is already going to spam, where nobody sees it to report it. The data may also be incomplete on days when your sending volume is low, which is common for a small sales team.

For the lookups, Cisco Talos and the Spamhaus checker both accept a domain or an IP. Treat them as an early warning: a listing is worth acting on, but a clean result doesn’t mean Gmail or Microsoft trusts you.

Microsoft offers no equivalent dashboard for domains. Its SNDS tool reports only on IP addresses you own, so teams sending from Google Workspace or Microsoft 365 have to rely on bounces, rejection codes and placement tests to see how Outlook treats their mail.

What is Sender Score, and does it apply to you?

Sender Score is a free score from Validity that rates a sending IP from 0 to 100 against other IPs, much like a percentile ranking. Validity states that “in most cases, scores are calculated on a rolling 30-day average.”

The catch for B2B teams is that it scores the IP, not your domain. If your reps send from Google Workspace or Microsoft 365, the IP belongs to Google or Microsoft, so the score describes their infrastructure rather than your sending. For those teams, improving Sender Score isn’t really possible or necessary. The signals in the table above, and the practices below, are what move the reputation you actually own.

Signs of poor reputation

Reputation rarely collapses in a single day. It usually slips first, and these are the signs to watch for:

• Bounce rates rising on lists that used to be clean
• Replies drying up from prospects who used to engage
• Placement tests showing mail landing in spam
• Delivery errors or rejection codes in your sending tool
• Prospects or colleagues mentioning they found your mail in spam
• Reps reporting that warm follow-ups are getting no traction

By the time several of these appear together, the damage has usually built up for a while. That’s why the practices below focus on what happens before the send.

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Best Practices to Improve Email Domain Reputation

The practices below are in order of where they act. The first ones work before a single message goes out, which is where a team has the most control and where problems are cheapest to fix.

Authenticate and align SPF, DKIM and DMARC

Authentication is the entry requirement, and alignment matters as much as having the records at all. Treat DMARC as a progression rather than a single setting. Start with a monitoring policy that only collects reports, use those reports to find every service that sends mail as your domain, then move to quarantine and finally to reject once every legitimate source passes. Our guide to DMARC reject explains that last step, and our setup guides for Google Workspace and Office 365 cover the records themselves.

Then make authentication part of every tool rollout. Whenever the team adds a sales engagement platform, marketing tool, CRM or support desk that sends as your domain, add it to SPF and set up its DKIM before the first message goes out, keeping in mind SPF’s lookup limit. Monitor all three records continuously, because they tend to break during routine changes nobody connects to email.

Verify every list before it is sent

Bounces and spam traps are the damage a team can stop most completely, by checking every address at three points: when it’s imported, before it enters a sequence, and on a regular cadence afterward, since contacts change jobs and mailboxes get closed. B2B lists need more than a basic check. In our census of all 500 Fortune 500 primary domains (validations run April to June 2026), 69% ran a catch-all domain, sat behind a secure email gateway, or both. On those domains, a standard verifier sees the server accept every address and passes contacts that later bounce.

Decide in advance what happens to addresses that come back “unknown”. Sending to them blind brings the bounces back. Dropping them all throws away real prospects, often at the accounts a team most wants to reach. The better rule is to keep them out of sequences until they’re resolved. To check a single address you’re unsure about, our free email verifier works without signup.

Respect per-mailbox limits and ramp volume gradually

Both major providers cap each mailbox. Google Workspace limits a user to 2,000 messages a day and 2,000 unique external recipients a day (500 on trial accounts). Microsoft 365 allows 10,000 recipients per user per day and 30 messages a minute, and it also sets an organization-wide daily limit on external recipients: when that’s exceeded, every user in the organization is blocked from sending to external recipients. A team running close to any of these limits has no room for error.

Ramp new mailboxes gradually rather than starting a new rep at full volume, and spread sends across the working day rather than releasing every sequence step at once. The same applies to new campaigns: add volume over weeks, not overnight. Our guide on how to warm up an email domain covers ramp-up schedules.

Separate outbound from your primary domain

Many teams send cold outreach from a separate domain, so a problem with prospecting doesn’t reach the domain their customers, finance and leadership rely on. There are two ways to do it. A subdomain (such as outreach.company.com) is easy to set up and recognizable to recipients, but it stays tied to the root domain: Google’s compliance status uses subdomain data and reports it against the primary domain. A secondary domain (such as getcompany.com) gives more separation, but it starts with no sending history.

Either way, the isolation is partial, and the new domain needs the same care as the main one: its own SPF, DKIM and DMARC records, a gradual warm-up, and a website or redirect so recipients who check it see a real company. Our guide to email subdomain best practices covers the setup.

Suppress fast and make leaving easy

Remove hard bounces and anyone who complains as soon as they appear, rather than at the next list cleanup. Make opting out easy: Yahoo requires bulk senders to honor unsubscribes within 2 days, and Gmail requires one-click unsubscribe on marketing mail from senders of more than 5,000 messages a day.

The common B2B gap is suppression that lives in only one tool. A prospect who unsubscribes from the marketing newsletter often keeps receiving sales sequences, because the sales engagement platform never got the update, and that’s exactly the person most likely to report the next email as spam. Keep one suppression list that every sending tool reads from, and stop sending to contacts who never reply once a sequence ends.

Govern the team’s senders

One shared domain means one rep’s list or volume affects everyone, and Microsoft’s organization-wide limit shows how literal that can be. Reputation has to be managed as a team rule, not a personal habit. Set clear rules for where lists can come from, rule out bought lists, require verification before any list is uploaded to a sequence, and cap daily volume per mailbox, with a ramp-up period for new reps.

Then review results per sender, ideally every week: bounce rate, complaints and replies for each mailbox. A problem that traces back to one rep in its first week is a coaching conversation. Left alone for a month, it can become a domain-wide recovery project.

How Allegrow protects sender reputation

The tools that protect a B2B team’s shared domain work at three points: before the send, at the moment of send, and once mail is going out. Allegrow covers all three, starting with verification.

Before the send, Allegrow verifies contacts with conclusive valid or invalid results on catch-all and gateway-fronted company domains, where many verifiers return “unknown”, and flags spam traps and known complainers. Verification through integrations is unlimited on the Unlimited Plan, so re-checking a list before every campaign carries no per-record cost. For teams building their own workflows, a SOC 2 certified API offers synchronous and asynchronous endpoints.

At the moment of send, the Safety Net checks contacts inside Outreach, Salesloft, Apollo and HubSpot just before a sequence step goes out, and pauses the risky ones. The Deliverability Leaderboard then shows risk per rep, which turns the team rules above into something you can actually check.

Once mail is going out, Allegrow monitors domain reputation on real enterprise domains, with daily spam and inbox placement tracking. It checks SPF, DKIM and DMARC every hour, so a broken record is caught the same day. Its warm-up runs automated positive interactions with real B2B inboxes, building the replies and engagement mailbox providers reward.

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How to Recover a Damaged Sender Reputation

Recovery works best in a fixed order, because each step depends on the one before it:

1. Stop sending from the affected domain or mailboxes. Every message sent while the cause is still there adds to the damage, so pause the sequences first, even if pipeline targets are close.
2. Find the cause. Check spam rate, compliance status and delivery errors in Postmaster Tools, bounce and rejection codes in your sending tool, and anything that changed recently: a new list source, a new rep, a new tool, a DNS edit.
3. Fix it at the source. Clean and re-verify the list if bounces or traps caused the drop, repair SPF, DKIM or DMARC if authentication failed, and remove whatever change triggered the spike.
4. Resume at low volume, to the recipients most likely to reply. Start with contacts who have engaged recently, then ramp gradually, so providers see the improved pattern before they see the full volume again.
5. Give the numbers time to settle. Google notes that after you fix an issue, it can take up to 7 days for changes to show in the Postmaster Tools dashboard, so judge progress over a week rather than day by day.

The most common mistake is switching to a brand-new domain without fixing the cause. That moves the problem rather than solving it: the same list and the same habits will damage the new domain too, and a new domain starts with no sending history to absorb mistakes, which makes it more fragile than the one you left.

Recovery also takes as long as it takes. No mailbox provider publishes a recovery timeline, and how long it lasts depends on what caused the damage. A broken DKIM record fixed the same day recovers very differently from months of sending to a stale list.

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The Hidden Costs of a Bad Email Reputation

Lost pipeline

The cost of poor reputation doesn’t show up as an error message. It shows up as meetings that never get booked. As an illustrative example: if 40% of a team’s sales emails land in spam, roughly 40% of its outreach never gets a chance to create pipeline. For a team expected to generate $1M in pipeline a month, that could mean up to $400,000 in opportunities that never start.

That loss is easy to misread. Reply rates fall, and the team blames the messaging, the market or the reps, while the real cause sits in a spam folder nobody checks.

Blocked domains and locked accounts

When reputation drops far enough, providers stop filtering mail and start rejecting it, and the domain itself becomes the problem. Because the domain is shared, so is the consequence: one rep’s bad list can stop mail from the whole company. We’ve seen cases where a CEO’s emails couldn’t reach investors because of damage caused by outbound prospecting on the same domain.

That’s the strongest case for the practices above. The rep who caused the damage and the people who pay for it are often not the same people.

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Conclusion

Sender reputation is now built mainly from complaints, bounces, authentication and sending consistency, and each mailbox provider judges it on its own data. Opens aren’t part of it, and the reputation dashboards most guides point to are no longer there to watch, so a team has to read its standing from spam rate, delivery errors, bounces and rejections instead.

For a B2B team, the payoff is protecting the shared domain before the send. That means verifying every list before it enters a sequence, keeping SPF, DKIM and DMARC monitored, and holding each mailbox to a sensible daily volume. Recovering a damaged domain is slower and less predictable than keeping it healthy, and the whole team pays for the time it takes.

To see what your current list would do to your domain, start a 14-day free trial and run up to 1,000 of your own company and catch-all contacts through Allegrow before your next send. You’ll see which ones would have bounced, including the addresses other verifiers return as “unknown”.

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FAQs

How fast can domain reputation change after a bad send?

Very fast. Domain reputation updates continuously based on what inbox providers see from your recent sending behavior and recipient reactions, so a single day of high bounces, spam complaints, or poor engagement can cause a noticeable drop.

Does domain reputation apply to the whole company or just one mailbox?

It applies at the domain level, meaning it can impact everyone sending from that domain. That’s why one team’s risky sending can create deliverability problems for other teams using the same domain.

What hurts sender reputation the fastest: bounces, complaints, or low engagement?

Spam complaints and spam traps are the fastest ways to lose trust, while high bounce rates can quickly signal poor list quality. Gmail asks senders to keep their spam rate below 0.10% and never reach 0.30%, so even a small number of complaints matters. Low engagement also hurts over time, because inbox providers treat ignored emails as a sign your messages aren’t wanted.

Can a single SDR damage the whole domain’s reputation?

Yes. If one sender repeatedly emails risky contacts, generates bounces, or triggers complaints, that negative behavior can reduce trust in the entire domain and affect inbox placement for other mailboxes too.

Can emailing inactive contacts hurt reputation even if they don’t complain?

Yes. Contacts who never reply and delete your mail without reading it send a negative signal, and over time that can push more of your mail into spam even when complaint rates stay low. Opens aren’t the measure here, since Google states it doesn’t track open rates.

How long does it take to recover a damaged domain reputation?

Often weeks to months, depending on what caused the damage. No mailbox provider publishes a recovery timeline, and Google notes that even after a fix, changes can take up to 7 days to show in Postmaster Tools. The recovery steps above set out the order that gives a domain its best chance.

What metrics should you monitor daily to protect reputation?

Track bounce rate, spam complaint rate, reply trends and inbox placement. Watching them together helps you catch a problem early, before it turns into widespread spam placement, especially now that Gmail no longer shows a reputation score to watch.