How to check IP reputation across providers?

Your IP's reputation isn't stored in one place. Every mailbox provider and blocklist operator runs their own scoring system, so checking just one tool gives you an incomplete picture. Here's how to cover the ground that actually matters.

Start with the mailbox providers

Gmail's Postmaster Tools is the most important starting point if you send any volume to Gmail addresses. It shows IP reputation as one of four levels (bad, low, medium, high) based on how Gmail users interact with your mail. If you haven't claimed your domain there yet, do it today.

Outlook's Smart Network Data Services (SNDS) gives you a traffic light rating for your IP across Microsoft's properties. Green means you're in good shape. Yellow means they're watching you. Red means mail is likely being blocked or junked.

These two cover a huge portion of consumer inboxes, so if both look clean, you're probably in reasonable shape with the mainstream providers.

Then check the blocklist aggregators

MXToolbox runs your IP against dozens of blocklists in one query. It's the quickest way to spot a listing you didn't know about. If something comes up red, note which blocklist flagged you. Not all blocklists carry equal weight with every receiving server, so a listing on an obscure one matters far less than a listing on Spamhaus.

Spamhaus itself is worth checking directly. Their SBL, XBL, and PBL lists are among the most widely referenced by enterprise mail systems and ISPs. A Spamhaus listing is the kind of thing that causes mail to be rejected outright, not just filtered.

Barracuda's lookup at BarracudaCentral shows your status on their blocklist, which is heavily used by corporate mail gateways. If your audience includes business email recipients, this one's worth checking.

For corporate and enterprise mail filters

Cisco's Talos Intelligence offers a public IP reputation lookup. Talos data feeds into a lot of enterprise spam filters, so if you're sending to business addresses and seeing delivery problems, Talos is worth a check. A "poor" score there won't show up in Gmail Postmaster Tools, which is exactly why you need to check multiple places.

What to do when scores disagree

It's pretty common to see a clean score in one place and a warning flag somewhere else. That usually means the problem is specific to a particular mailbox provider's user base or a particular blocklist operator's criteria. A poor Talos score doesn't mean Gmail is rejecting you. A yellow SNDS rating doesn't mean you're blocklisted anywhere.

When scores disagree, dig into where the complaints are coming from. High complaint rates from Outlook users will hurt your SNDS score without touching your Gmail Postmaster rating. The reverse is also true. Treat each data source as one piece of evidence, not the whole verdict.

But if you're trying to understand whether a poor reputation and a blocklisting are actually the same thing, they're not always. And if you're watching things recover over time, the timeline is slower than most senders expect.

So you can also run a quick blocklist check using our free tool if you want a fast snapshot without setting up accounts anywhere. Or if something's actively broken and you need a second opinion, our SOS hotline is free.