IEmail Deliverability Glossary

IP Reputation

The trust score ISPs assign to a specific sending IP based on bounce rates, complaint rates, spam trap hits, and sending pattern consistency.

IP reputation is the trust score assigned to a specific IP address by ISPs based on the email-sending behavior associated with that IP.

Reputation signals tracked per IP:

Volume and sending pattern consistency
Bounce rates
Spam complaint rates
Spam trap hits
Blacklist status
Authentication pass rates (does the sending IP have matching PTR? Is it in the SPF record?)

Tools to check IP reputation:

Google Postmaster Tools — Gmail-specific IP reputation
Microsoft SNDS — Outlook/Hotmail IP data
Validity Sender Score (senderscore.org) — Score from 0–100; above 80 is good
Talos Intelligence (talosintelligence.com) — Cisco's IP reputation lookup
Barracuda Central — Barracuda's reputation lookup

Frequently Asked Questions

How do I check my sending IP's reputation?

The most reliable reputation checks are: Google Postmaster Tools for Gmail-specific IP data (requires your domain to be verified), Microsoft SNDS at postmaster.live.com for Outlook/Hotmail reputation, Validity Sender Score at senderscore.org for a 0–100 composite score, and Cisco Talos Intelligence at talosintelligence.com for a Good/Neutral/Poor verdict. MXToolbox Super Tool (mxtoolbox.com/SuperTool.aspx) provides blacklist status across 100+ lists in one lookup. Monitor these weekly during warm-up and monthly once you reach your target volume.

Can I fix a damaged IP reputation?

IP reputation damage can be repaired more easily than domain reputation damage because you can switch IPs. If your current IP has serious reputation problems (Spamhaus listing, Microsoft SNDS Red status, Sender Score below 60), moving to a new IP and warming it up from scratch is often faster than rehabilitating the damaged one. If you want to recover the existing IP, stop sending from it for 30–60 days while the negative signals age out, get delisted from any blacklists, and then restart with a very gradual warm-up. Never try to 'blast through' IP reputation problems with high volume — it makes the damage permanent.

Does IP reputation or domain reputation matter more for deliverability?

Both matter, but domain reputation is increasingly the more durable and impactful signal. As email shifted from fixed on-premise mail servers to cloud providers (Google Workspace, Microsoft 365) where IPs change frequently, ISPs placed more weight on domain-level signals that stay consistent regardless of which IP is sending. Gmail especially is known to weight domain reputation heavily. However, IP reputation still matters significantly for Outlook/Exchange and enterprise mail gateways. The safest approach: warm up both simultaneously so neither is a weak point.

Related Terms

Domain Reputation

The permanent trust score ISPs assign to your sending domain based on historical behavior. Unlike IP reputation, a damaged domain reputation can take months to recover.

IP Warm-Up

The process of gradually increasing sending volume from a new IP address to build positive ISP reputation before scaling to full send volume.

Dedicated IP

An IP address used exclusively by a single sender. Gives full reputation control but requires complete warm-up from zero before high-volume sending.

Sender Score (Validity Sender Score)

A third-party IP reputation metric scored 0–100 by Validity. Scores above 80 indicate healthy delivery; below 60 signals active blocking. One signal among many.

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