Proxy IP reputation: why a site blocks some addresses, and how to check yours

A site cannot see you through a proxy; it sees the proxy’s address and judges it by what is known about that address: whether it belongs to a hosting company or a home internet provider, whether it is on an abuse list, and what other people did from it before you. A datacenter address is easy to recognise as a server, a shared address carries the other buyers’ history, and a residential address can still be flagged as a proxy. Check the address before you rely on it, and pay for one of your own when its history matters.

Answer · The live comparison uses prices checked up to Oct 24, 2026; every figure in the text keeps the date it was checked.

What a site knows about an address

Sites rarely judge an address on its own traffic alone. They buy or share lists that sort addresses into kinds, and three kinds of list matter for a proxy:

• Who the address belongs to. MaxMind’s Anonymous IP database, one such list, flags “IP addresses associated with hosting services that are likely to be used as anonymizers”, and separately flags residential proxies: “IP addresses on a suspected anonymizing network that are registered under residential ISPs” (MaxMind). Every datacenter proxy sits in a hosting company’s range, so this is the first check it fails (residential vs datacenter proxies).
• Abuse reports. AbuseIPDB is “a central repository for webmasters, system administrators, and other interested parties to report and identify IP addresses that have been associated with malicious activity online” (AbuseIPDB).
• Blocklists. Spamhaus’s Exploits Blocklist is “a realtime database of IP addresses used by hijacked devices compromised by 3rd party exploits” (Spamhaus). Lists like it were built to filter email; any service can look an address up in them.

A site may block a listed address outright, slow it down or show a challenge page; which it does is the site’s choice, not the proxy’s.

Why an address can be flagged before you use it

An address keeps its record when it changes hands. Spamhaus says this of home connections: “a user may be assigned an IP address from their provider that is listed in the XBL because of the situation of a previous user of that IP address” (Spamhaus). The same holds for proxies:

• Shared proxies are used by several buyers at once, so one buyer’s abuse is on every buyer’s record (shared vs dedicated proxies).
• Dedicated proxies are yours alone while you rent them, but many were someone else’s before. Evomi sells its static residential addresses in grades, shared, private and “virgin”, and says the “Grades differ by how many other customers have used the address, not by speed” (Evomi).
• Rotating residential proxies change address on every request or session, so a flagged address is gone at the next rotation; what you buy is the record of the whole pool, not of one address (what is a backconnect proxy).
• IPv6 addresses are often judged in blocks: Spamhaus’s list “lists /64 subnets of IPv6 addresses”, so one address’s record covers its neighbours (IPv4 and IPv6 proxies).

How to check an address

1. Find the address the proxy gives you. Ask a “what is my IP” service through the proxy, for example curl -x http://USER:PASS@HOST:PORT https://api.ipify.org, which prints the address the site sees (proxy logins).
2. Look it up on Spamhaus’s IP and Domain Reputation Checker and on AbuseIPDB.
3. A dedicated address that is listed on delivery is worth raising with the provider at once, inside any refund window it gives (proxies with a refund window).

What it means for what you buy

• Your target sites check nothing: a shared datacenter address is the cheapest way in, and its history rarely matters.
• Your target sites check who owns the address: a static residential (ISP) address is registered to an internet provider rather than a hosting company (ISP vs residential proxies).
• Your work depends on one address keeping a clean record: buy it dedicated, check it on the first day, and keep your own use clean, because from then on its record is yours.