How to Check if Your Email is Blacklisted
MailMoxie’s new MailMoxie’s Blacklist Checker helps teams identify whether their sending domain or IP has been flagged by major blacklist providers, and understand how those listings affect sender reputation and inbox placement.
What is an email blacklist?
An email blacklist is a database maintained by an organization that tracks domains or IP addresses associated with suspicious or unwanted email behavior. Mail servers reference these blacklists when deciding whether to accept, filter, or block incoming messages.
If your domain or IP appears on one or more blacklists, emails sent from that source are more likely to be filtered to spam or rejected entirely.
Blacklisting does not automatically mean you are “sending spam.” Listings can occur for a variety of technical and historical reasons.
Common reasons domains and IPs end up on blacklists
Blacklist listings often result from patterns that accumulate over time, not a single bad campaign.
Some common causes include:
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Misconfigured DNS or authentication records
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Sending from legacy subdomains no longer actively monitored
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Sudden spikes in volume that trigger automated defenses
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Shared infrastructure issues at the ESP or hosting level
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Historical reputation from past senders using the same IP
Because these issues are not always visible in inbox previews or basic QA checks, they are easy to miss without explicit blacklist monitoring.
How blacklists affect sender reputation
Blacklists are one signal among many used to assess sender reputation. While inbox providers do not rely on any single list, being flagged can influence how your mail is treated, especially when combined with other risk factors.
In practice, blacklist listings can lead to:
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Reduced inbox placement
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Increased spam filtering
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Inconsistent delivery across providers
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Suppression at the server level
This is why blacklist checks are best used as an early warning system, not a last-ditch troubleshooting step.
How MailMoxie’s blacklist checker works
MailMoxie’s Blacklist Checker scans your sending domain and related infrastructure against known blacklist sources. The goal is to surface potential reputation risks before they escalate into deliverability problems. Results are presented alongside other deliverability and configuration signals, allowing teams to evaluate blacklist findings in proper context rather than in isolation.
MailMoxie focuses on detection, clarity, and visibility, helping teams understand when action is needed and where to investigate next.
Blacklist checks as part of reputation management
Blacklist status can change over time. A clean domain today does not guarantee the same outcome next month, especially as templates evolve, infrastructure changes, or sending patterns shift.
That’s why blacklist checking works best as part of an ongoing sender reputation process, not a one-off diagnostic. By including blacklist checks in routine email testing, teams can catch emerging issues earlier, validate fixes after changes, and reduce the risk of long-term reputation damage.
When blacklist monitoring matters most
Blacklist checks are especially valuable when:
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Launching a new sending domain or subdomain
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Migrating ESPs or infrastructure
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Reusing or modifying legacy templates
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Seeing unexplained drops in engagement or inbox placement
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Scaling volume after a quiet sending period
In these moments, reputation issues often surface, and blacklist visibility can provide critical context.
Check to see if your email domain is blacklisted
Check your current blacklist status with MailMoxie’s Blacklist Checker.