How to Check Your IP Reputation: Email Deliverability Guide

Your IP reputation is one of two scores that decide whether your emails hit the inbox or land in spam. Many businesses never check their IP reputation, just send emails and hope for the best. Then their open rates tank and they can't figure out why.

Every time you send an email, Gmail, Yahoo, and Outlook watch what happens next. Do people open it? Click links? Mark it as spam? All this activity builds a reputation score tied to your sending IP address. High scores get you into inboxes. Low scores land you in spam.

This guide shows you exactly how to check your IP reputation, how it differs from domain reputation, what impacts it, and how to fix problems before they hurt your deliverability.

TL;DR: How to Check IP Reputation

Free tools to check IP reputation:

• SenderScore: Overall IP reputation score (0-100 scale)
• Microsoft SNDS: Outlook/Hotmail IP reputation data
• Google Postmaster Tools: Gmail spam rate and authentication data
• Talos Intelligence: Cisco's IP and domain reputation database
• Spamhaus: Most respected blocklist checker
• MXToolbox: Quick blacklist checking across 100+ lists

Key reputation factors:

• Complaint rates: How often recipients mark emails as spam
• Engagement rates: Opens, clicks, replies (positive signals)
• Bounce rates: Invalid email addresses (negative signals)
• Volume consistency: Sudden spikes can hurt reputation
• Authentication: SPF/DKIM/DMARC records improve reputation

What to watch out for: Building IP reputation takes weeks. Destroying it takes days. Send good emails to people who actually want them. Check your reputation weekly to catch problems fast.

For understanding domain reputation, see our how to check domain reputation guide. For understanding why emails go to spam, check why are my emails going to spam.

IP Reputation vs. Domain Reputation

Before diving into the tools, it helps to understand what makes IP reputation different from domain reputation. Most senders treat them as the same thing, but they're not.

IP reputation is tied to the specific IP address your emails are sent from. It reflects the sending history of that IP — how much mail it sends, how many complaints it gets, how many bounces it generates. If you switch to a new IP address, you start with zero reputation and have to build it from scratch through a process called IP warming.

Domain reputation is tied to your sending domain (e.g., yourcompany.com). It's more portable — it follows you when you change email providers or IP addresses. Domain reputation is influenced by factors like how long your domain has been active, your authentication setup, and the long-term sending behavior across all IPs you've ever used.

The practical difference matters a lot:

Modern ISPs, especially Gmail, put more weight on domain reputation than IP reputation. Gmail has been moving toward domain-based filtering for years. That said, IP reputation still matters. A blacklisted IP will get your emails blocked regardless of how clean your domain looks. You need both in good shape.

The tools you use to check each are different. SenderScore and Microsoft SNDS are IP-specific. Google Postmaster Tools has historically shown both, but removed its IP and domain reputation scores in September 2025. For IP reputation specifically, the tools below are your best options.

What Is IP Reputation?

IP reputation is your email sending score at the infrastructure level. ISPs track everything people do with emails from your IP address. Open them? Good. Delete without reading? Bad. Mark as spam? Really bad.

Think of it like a credit score for your sending server. Just like banks check your credit before giving you a loan, ISPs check your IP reputation before delivering your emails. High score means straight to the inbox. Low score means straight to spam.

Here's what ISPs track to calculate your IP reputation:

Complaint rates matter most. When someone hits the spam button, it's a vote against your IP. Too many complaints and ISPs stop trusting mail from that address.

Engagement rates show if people want your emails. Opens, clicks, and replies tell ISPs your emails are welcome. No engagement tells them you're probably sending junk.

Bounce rates signal list quality. Sending to fake or dead email addresses makes you look like a spammer who bought a list.

Volume consistency shows you're legitimate. Real businesses send steadily, while spammers blast millions at once.

Authentication proves you're who you say you are. SPF, DKIM, and DMARC records show ISPs you're not spoofing someone else's domain.

ISPs keep their exact scoring methods secret, but they give you tools to see how you're doing.

Why IP Reputation Matters

Your IP reputation controls your email fate at the infrastructure level.

With good IP reputation, your emails sail through filters. ISPs trust your sending server, so they deliver fast and reliably. With bad IP reputation, even a handful of emails might get blocked entirely. Not just filtered to spam, but rejected outright.

Here's what actually happens based on your IP reputation:

Good reputation (80–100 score): Your emails get delivered without friction. ISPs recognize your IP as a trustworthy sender and process your mail quickly.

Medium reputation (50–79 score): Some emails reach inboxes, others hit spam. ISPs are watching closely. Any mistakes and you drop further.

Poor reputation (0–49 score): Most emails go straight to spam or get blocked at the connection level. ISPs may throttle your sending or refuse connections entirely.

The difference is dramatic. A sender with good IP reputation might see 95% inbox placement. A sender with poor IP reputation might see 5%. Same email, same content, totally different results.

That's why checking IP reputation is one of the first things to do when deliverability drops.

How to Check IP Reputation

You need to check your IP reputation regularly. Here are the best free tools that actually work:

SenderScore

SenderScore gives you a quick reputation score from 0 to 100 for your sending IP. It's run by Validity and is one of the most widely referenced IP reputation scores in the industry.

To check your score:

1. Go to https://www.senderscore.org
2. Type in your IP address
3. Get your score instantly

The results show more than just a number. You'll see how your reputation has changed over time and what factors are helping or hurting you.

Scores above 80 are good. Between 70–80 is okay, but below 70 means you have work to do. If it goes below 50 means you're in trouble.

SenderScore shows general IP reputation, not how specific ISPs see you. Gmail might have a different view than Outlook. That's why you need ISP-specific tools too.

Microsoft SNDS (Smart Network Data Services)

SNDS shows exactly how Microsoft (Outlook, Hotmail, Live) views your sending IPs. This is crucial since Microsoft handles hundreds of millions of business and consumer email accounts.

SNDS is strictly IP-based. You register the IPs you own and get data about traffic from those IPs. It does not provide domain-level reputation data.

To set it up:

1. Go to https://sendersupport.olc.protection.outlook.com/snds
2. Sign in with a Microsoft account and request access to your IPs
3. Start seeing your Microsoft-specific data

The dashboard shows complaint rates, spam trap hits, and your overall reputation color. Green is good, yellow means caution, and red means Microsoft is blocking or filtering your mail.

Pay attention to the complaint rate. Microsoft wants it below 0.1%. Above 0.3% and you're heading for trouble.

Google Postmaster Tools

Google Postmaster Tools provides Gmail-specific data about your sending. It's a non-negotiable tool since Gmail is the largest email provider.

Here's how to set it up:

1. Visit https://postmaster.google.com
2. Add your domain and verify it with a DNS record
3. Wait 24–48 hours for data to appear

Google retired its IP reputation and domain reputation scores in September 2025. The "High / Medium / Low / Bad" scores you may have seen referenced in older guides are no longer available.

What you still get is valuable: your spam rate (the percentage of emails marked as spam by users), authentication status for SPF, DKIM, and DMARC, and delivery error data. Gmail also now provides a compliance dashboard showing whether you meet their bulk sender requirements.

Just as Microsoft, Gmail wants your spam rate below 0.1%, and you're in danger if it hits 0.3%. Anything above that and Gmail will start blocking your emails.

Check this weekly. Gmail's view of your sending can change quickly, especially if you change your sending patterns or list quality drops.

Talos Intelligence

Cisco's Talos Intelligence is one of the largest commercial threat intelligence operations in the world. Their Reputation Center provides IP and domain reputation data based on a massive volume of real-world email traffic and threat data.

To check your IP:

1. Go to https://www.talosintelligence.com/reputation_center
2. Enter your IP address
3. See your reputation status and category

Talos assigns IPs to categories like Favorable, Neutral, Unfavorable, and Poor. A Poor or Unfavorable rating from Talos can affect deliverability to organizations using Cisco's email security products, which are widely deployed in enterprise environments.

Unlike SenderScore, Talos also covers web reputation and threat intelligence, so it gives you a broader picture of how your IP is perceived across security systems, not just email filters.

Spamhaus

Spamhaus runs some of the most widely used and respected blocklists in the world. Being listed on a Spamhaus blocklist is serious. Many ISPs and corporate mail servers use Spamhaus data to reject mail outright.

To check your status:

1. Go to https://check.spamhaus.org
2. Enter your IP address
3. See if you're listed on any Spamhaus blocklists

Spamhaus maintains several IP-focused blocklists, including the Spamhaus Blocklist (SBL) for known spam sources, the Exploits Blocklist (XBL) for compromised devices, and the ZEN combined blocklist. If you're listed, follow their removal process exactly. They're thorough and you'll need to demonstrate you've fixed the underlying problem before they'll delist you.

MXToolbox

MXToolbox is your Swiss Army knife for email diagnostics. It checks if you're on any of 100+ email blacklists in one shot.

To check your IP:

1. Head to https://mxtoolbox.com
2. Enter your IP address
3. Click "Blacklist Check"

Within seconds, you'll see if you're on any blacklists. Green checkmarks are good. Red X marks mean you're listed and need to request removal.

MXToolbox also checks your DNS setup, authentication records, and general email health. It's perfect for a quick health check, but it won't tell you how specific ISPs view your overall sending behavior — for that, use the ISP-specific tools above.

Use MXToolbox when deliverability suddenly drops. Being on even one major blacklist can tank your inbox rates.

Understanding IP Types: Shared vs. Dedicated

Your IP type affects how you monitor and manage reputation:

Shared IPs mean you share reputation with other senders on the same IP pool. Your email service provider manages the IP reputation. One bad sender can hurt everyone on the pool but reputable providers monitor this closely and remove bad actors quickly.

Dedicated IPs give you full control. Your reputation is yours alone. This is great if you send high volume consistently (typically 100,000+ emails per month). Below that threshold, a dedicated IP can actually hurt you. ISPs need to see consistent sending volume to build trust, and sporadic sending from a dedicated IP looks suspicious.

Most businesses do better with shared IPs from reputable providers. You get the benefit of consistent volume and professional management without the complexity of warming up and maintaining your own IP.

IP Warming: Building Reputation From Scratch

Got a new dedicated IP? You can't just start blasting emails. ISPs don't trust new IPs, so you need to warm them up gradually. The process typically takes 4 to 8 weeks depending on your target volume.

Week 1: Start tiny. Send to your most engaged subscribers only - people who opened emails in the last 30 days. Begin with a small daily volume and double it every few days.

Weeks 2–3: Keep increasing volume steadily and watch your metrics closely. If complaint rates or bounce rates spike, slow down and fix the issue before continuing.

Weeks 4–6: If metrics look healthy, continue increasing toward your normal sending volume. Aim for gradual ramps of no more than 50% per week.

During warming, never send to your full list. One complaint spike during the warming period can set you back significantly.

If you're switching email providers, warm up the new IPs before shutting down the old ones. Run both in parallel for a few weeks to prevent deliverability disruptions during the transition.

Factors That Affect IP Reputation

Knowing what moves your reputation up or down helps you fix problems fast.

Complaint Rates

Complaints kill IP reputation faster than anything else. Every time someone hits the spam button, it's a black mark against your sending IP.

ISPs get nervous when complaint rates climb above 0.1%. That's just one complaint per thousand emails. Hit 0.3% and you're in the danger zone. Above that threshold, Gmail, Microsoft and Yahoo will start blocking your emails outright.

Here's how to keep complaints low:

First, make unsubscribing dead simple. Put the link at the top of your emails, not buried at the bottom. One click, done. People who can't unsubscribe easily will mark you as spam instead.

Second, send stuff people actually want. Sounds obvious, but most senders blast every subscriber with every message. Segment your list and send relevant content to the right people.

Third, set expectations upfront. Tell people what they're signing up for. Daily emails? Weekly? Sales only? When people know what's coming, they complain less.

Finally, clean your list regularly. Remove anyone who hasn't opened in 6 months. They're not interested anymore, and keeping them just increases complaint risk.

Engagement Rates

ISPs watch what people do with your emails. Opens, clicks, replies, and forwards all boost your IP reputation, while ignored emails hurt it.

Gmail even tracks if people move your emails from spam to inbox (a huge positive signal) or from inbox to spam (a huge negative signal). They also notice if people add you to contacts or reply to your emails.

To boost engagement, quality beats quantity every time. Send one great email instead of three mediocre ones. Your best customers should get your best content.

Timing matters too. Test different send times to find when your audience actually checks email. Tuesday at 10am might work for B2B. Saturday morning might work for hobbyists.

Most importantly, send to people who actually open your emails. Segment out engaged subscribers and focus on them. Better to have 1,000 engaged subscribers than 10,000 who never open.

Bounce Rates

Bounces tell ISPs you're not maintaining your list properly. Too many bounces and they assume you bought a list or you're spraying emails everywhere.

There are two types of bounces:

Hard bounces mean the email address doesn't exist. Remove these immediately, as sending to them again will hurt your reputation.

Soft bounces are temporary problems like inbox full or server down. These might work later, but after 3–5 soft bounces, treat them as hard bounces and remove them.

Keep bounce rates below 2%, as above 5% ISPs start blocking you. Above 10% and you're probably already blocked.

To prevent bounces, use double opt-in. Make people confirm their email address before adding them to your list. Yes, you'll get fewer signups. But the ones you get will be real.

Volume Consistency

ISPs get suspicious when sending patterns change suddenly. If you normally send 1,000 emails a day then suddenly blast 50,000, they think you've been hacked or you're spamming.

Consistency builds trust. Send regularly at predictable volumes and if you need to increase volume, do it gradually. Add no more than 20–50% more each week, not 10x overnight.

If you only send monthly, consider sending smaller emails weekly instead. Sporadic senders have worse reputation than consistent senders, even at lower volumes.

When you do need to send a big campaign, spread it out. Instead of blasting 100,000 emails at once, send 20,000 per hour over 5 hours. Your servers will thank you, and so will ISPs.

Authentication

Authentication proves you're allowed to send from your domain. Without it, ISPs assume you're a spammer pretending to be someone else.

Three records matter:

SPF tells ISPs which servers can send email for your domain. It's a DNS record listing your approved sending IPs.

DKIM adds a digital signature to your emails. It proves the email hasn't been tampered with in transit.

DMARC tells ISPs what to do if SPF or DKIM fail. It also sends you reports about who's using (or abusing) your domain.

Setting these up wrong is worse than not having them at all. A broken SPF record can block all your emails. Take time to get it right.

Most email services provide the exact records you need to add. After adding them, use MXToolbox to verify they're working. Once set up, check them monthly. Things can break when you change email providers or add new sending services.

How to Improve IP Reputation

Fixing bad IP reputation takes work, but it's absolutely doable. Here's your action plan:

Start monitoring today. Set up Microsoft SNDS this week. Check SenderScore for a quick baseline. Put a weekly reputation check in your calendar. You can't fix what you don't measure.

Fix authentication first. Broken SPF, DKIM, or DMARC records are easy wins. Most problems come from simple typos or outdated records. Use MXToolbox to check yours right now. If anything's broken, fix it before sending another email.

Clean your list ruthlessly. Remove anyone who hasn't opened in 6 months and all hard bounces immediately. Yes, your list will shrink, but a smaller engaged list beats a large dead one.

Make unsubscribing easier than complaining. Put an unsubscribe link at the top of every email. Make it one-click. No "are you sure?" pages, no required surveys. People who want out should get out instantly.

Slow down if you're in trouble. If your reputation is poor, cut your sending volume in half. Focus on your most engaged subscribers only. Once reputation improves, slowly increase volume by 20% per week.

Be patient. IP reputation doesn't improve overnight. It takes 4–8 weeks of consistent good behavior to see real improvement. But once it improves, your deliverability problems disappear.

The fastest way to improve? Stop sending to people who don't want your emails. It's that simple.

Where Bento Fits: IP Reputation Monitoring Included

If you're tired of juggling multiple tools to monitor IP reputation, here's how Bento simplifies things.

IP reputation monitoring built in. Bento watches your IP reputation across major ISPs. You get alerts before problems hurt deliverability. No need to check five different tools every week.

Authentication done right. Bento generates your exact SPF, DKIM, and DMARC records - you just copy, paste, and it's done. We verify everything's working and alert you if something breaks.

Smart sending patterns. Bento automatically spreads large sends over time. Send to 50,000 people and Bento delivers them in batches, not all at once. ISPs see consistent, responsible sending instead of suspicious spikes.

Automatic list cleaning. Bounces get removed instantly, complainers get suppressed immediately and inactive subscribers get flagged for removal. Your list stays clean without constant maintenance.

When Bento makes sense: You want email that just works. You're tired of checking multiple reputation tools and you want someone else to worry about authentication and delivery patterns while you focus on creating great emails.

When other tools make sense: You need super detailed ISP data for troubleshooting specific issues. You're managing multiple dedicated IPs across different providers. You're building custom email infrastructure from scratch.

Bento handles the technical stuff so you can focus on what matters: sending emails people actually want to read. Start your 30-day free trial today or book a demo.

Ready to Check Your IP Reputation?

Here's your action plan for this week:

Day 1: Set up monitoring Sign up for Microsoft SNDS today. Add your sending IPs. Check SenderScore for a quick baseline. These take 30 minutes to set up and give you data you can act on immediately.

Day 2: Check your authentication Run your domain through MXToolbox. Are SPF, DKIM, and DMARC all passing? If not, fix them before sending another campaign. This alone can boost your deliverability significantly.

Day 3: Audit your list Pull engagement data for the last 6 months. Anyone who hasn't opened a single email needs to go. Run your list through an email validator to catch bad addresses.

Day 4: Fix your unsubscribe process Send yourself a test email and try to unsubscribe. If it takes more than two clicks or asks for a password, fix it. Make unsubscribing stupidly easy.

Day 5: Review and plan Look at your monitoring data. Where are the problems? High complaints? Low engagement? Make a plan to fix the biggest issue first.

Going forward: Check reputation tools every Monday. It takes 5 minutes and catches problems before they explode. Clean your list monthly, segment your sends and focus on quality over quantity.

Helpful resources: Learn about domain reputation in our how to check domain reputation guide. Figure out spam problems with why are my emails going to spam. Explore tools in our email deliverability tools guide.

Your IP reputation determines if people see your emails. Start monitoring it today. Fix the easy stuff first, but be patient with improvements. In a few weeks, you'll see the difference in your inbox rates.