My IP Address Is Blacklisted: How to Check and What to Do

1. What a blacklist is, and why the list name matters

"Blacklist" is a catch-all word. In practice you will meet lists that mail systems query before accepting a message, such as the SpamCop Blocking List (SCBL). SpamCop describes the SCBL as a list of IP addresses that have transmitted reported email to SpamCop users; it is time-based, which means listings clear automatically when reports stop.

The list name in a lookup matters more than the yes or no, because it tells you what kind of problem you have. A listing about mail behaviour calls for a mail fix. A listing on an address you only browse from is a different situation, covered in Section 4.

• Sources:
• SpamCop Blocking List

2. First steps: check the address and read the reason

1. Take the exact IP from the failure

   A bounce message (a non-delivery report, NDR) usually names the sending address. Microsoft's documentation shows NDRs such as "550 5.7.606-649 Access denied, banned sending IP" that carry the IP and tell you where to ask for removal.

2. Use the operator's own lookup,

   not a third-party mirror. Spamhaus publishes an IP and domain reputation checker that it describes as a free tool, and SpamCop offers a lookup form on its blocking-list page.

3. For SpamCop you can also query DNS

   Reverse the octets of the IP and query them under the blocklist domain, for example 4.3.2.1.bl.spamcop.net for 1.2.3.4, using nslookup, host or dig. An answer such as 127.0.0.2 means the IP is listed; a non-existent-host answer means it is not.

4. Read the reason, not only the result

   The Spamhaus troubleshooting article lists what its checker tests: whether the IP has a reverse DNS (PTR) record, whether there is a valid HELO domain that matches the reverse DNS record, and whether the values agree with each other.

5. If the check looks clean but mail is still refused,

   Spamhaus's FAQ says a DNS resolver issue can hide a listing, and that if a recent removal has not taken effect yet, some networks update slowly and you should wait one to two hours.

3. Case 1: the listed IP is your own mail server or sending IP

If you run the mail server, you are the one who can fix the cause and ask for a review. Work through the steps in order.

• Sources:
• Spamhaus: troubleshoot your listing
• Spamhaus: general questions
• Spamhaus: residential networks FAQ
• Microsoft: delist portal and error 5.7.511

3. Case 1: the listed IP is your own mail server or sending IP

1. Fix the cause first

   Spamhaus's troubleshooting article treats removal as the last step, after the issues the checker finds are fixed.

2. Make the identity consistent

   The article's resolution steps require the HELO domain to resolve to the sending IP, the reverse DNS to resolve to a fully qualified domain name, and the reverse record to match the HELO domain and resolve back to the sending IP. If any check shows a red cross, the article says any removal request is likely to be unsuccessful.

3. Look for a compromised device

   Spamhaus's residential-network FAQ describes a device behind the address (for example a smartphone or streaming stick) making unauthorised SMTP connections on port 25. Its advice: restrict port 25 so only the mail server uses it, make all user devices send mail with SMTP authentication on ports 587 or 465, and remember that limiting port 25 stops the spam but the affected device still needs to be cleaned or removed.

4. If you do not run the mail server,

   contact whoever does, such as your administrator, ISP or email provider. Spamhaus says removal requests must come from the registered owner of the IP or domain, and others should contact their service provider.

5. Use the checker's request flow and only that

   Spamhaus says it cannot handle removal requests made through other channels such as email. It also says requests should not be made through a VPN or from a free or disposable email address. If automatic removal is not permitted, the checker raises a ticket for review.

6. Do not expect a guarantee

   Following the article gives the IP the best chance of removal, but approval is decided by the operator.

7. SpamCop works differently

   Because the SCBL is time-based, an address drops off automatically once reports stop; there is no request to file with an owner.

8. If a Microsoft 365 recipient refuses your mail,

   Microsoft provides the Office 365 Anti-Spam IP Delist Portal for errors in the 5.7.606–649 range. You enter the address that received the NDR and the IP from the error, one of each per visit, confirm through the email you receive and select Delist IP. Microsoft notes that this can take up to 24 hours or longer. For error 5.7.511 the portal cannot be used: you send the NDR code and IP to the delist address given in the error, and Microsoft says it will respond within 48 hours.

4. Case 2: the listed IP is only the address you browse or connect from

Here the situation differs in one decisive way: you probably do not control the address, and the listing is about mail rather than browsing.

• Sources:
• Spamhaus: general questions
• Spamhaus: residential networks FAQ

4. Case 2: the listed IP is only the address you browse or connect from

1. Decide whether the listing can affect you

   A mail blocklist is consulted by receiving mail systems. A browsing session does not send mail, so a listing on your exit address does not by itself describe your browsing.

2. Find out what kind of address you are on

   Whether it is a residential, ISP or datacenter address decides who can act. The guides on checking IP type and static and dynamic IPs explain the difference.

   • checking IP type
   • static and dynamic IPs

3. Confirm the listing and read the reason

   If the reason is mail behaviour, such as unauthorised SMTP connections on port 25 from a device behind the address, the address belongs to an access network and the fix sits with that network's operator.

4. If it is your home connection, ask the ISP

   Spamhaus advises, for a dynamic address with no mail server, asking the ISP to block or disable port 25 for the connection, and sending mail through the ISP's mail server or a trusted third-party service with authentication on ports 587 or 465. If the address sits behind carrier-grade NAT, Spamhaus says the traffic may come from another customer sharing the same address pool, and only your IP provider can investigate that.

5. Do not file a removal request for an address you do not own,

   since Spamhaus accepts removal requests only from the registered owner.

6. If the address came from a proxy service you are testing,

   treat the listing as a data point. The IP purity check guide covers looking at an exit address's reputation before you rely on it, and checking a proxy IP's location confirms where a session appears from.

   • IP purity check guide
   • checking a proxy IP's location

7. If one exit works and another does not,

   check the connection itself before blaming the address, because connection failures often come from credentials, protocol or endpoint settings.

   • connection failures

8. Match the address type to the job

   For work that needs the same exit each time, a static ISP IP stays fixed for the lease term. Proxy302 rents these per IP, from static ISP proxies, and you pick the protocol when you generate the proxy: HTTP on port 2222 or SOCKS5 on port 3333 at proxy.proxy302.com.

   • static ISP proxies

5. When there is no request you can file

An IP change only alters the network address a service sees; decisions about accounts stay with the platform. These steps still help:

5. When there is no request you can file

1. Step 1

   Write down the list name, the date, the stated reason and any evidence for a later conversation with your ISP or provider.

2. Step 2

   Fix anything on your side that really sends mail from the address, following the port 25 and authenticated-submission advice above.

3. Step 3

   Ask the party that owns the address to act, if that is not you.

4. Step 4

   Look the address up again later, since a recent removal can take an hour or two to show.

5. Step 5

   For the task itself, test from an address type that fits the job while the listing question is handled.

How to do it with Proxy302

Proxy302 rents static ISP IPs that stay fixed for the lease term, so you can check an address once and keep using the same one.

Look up the IP you receive the same way, then use the gateway proxy.proxy302.com with the protocol you generated: HTTP on port 2222 or SOCKS5 on port 3333.

• IP purity check
• IP type check
• Static ISP proxies
• Proxy connection failed

How to do it with Proxy302: steps

1. Step 1

   Open the product page that fits (static ISP, rotating residential or the ISP for AI subscriptions) and pick the region, traffic or lease term, and quantity. For per-IP products also choose HTTP or SOCKS5.

2. Step 2

   After the proxy is generated, open My assets and copy HOST, PORT, USERNAME and PASSWORD.

3. Step 3

   Open https://ipinfo.io/json through the proxy and check that the country and org fields (ASN and organization) are what you expected.

4. Step 4

   Then compare network type and native or broadcast on the IP purity check page. Two tools disagreeing is normal; go by your actual use.

Prices and limits

Rotating residential starts at US$1.50 per GB on the Budget line and US$5 per GB on the Premium line; larger packages are cheaper per GB, and purchased traffic has no expiry. A static ISP IP is US$0.50 for one day or US$7.99 for 30 days, the same in every country, fixed for the lease. A datacenter IP is US$0.25 for one day or US$3.99 for 30 days. Stock changes daily, so go by the order page. The smallest purchase is 1 GB of traffic or one IP for one day. Changing IP does not lift a restriction or raise a limit; what happens to an account is up to the platform.

• Sources:
• Proxy302 product facts and price list

Proxy302 at a glance

Prices are in PTC, paid from the wallet; 1 PTC = US$1. There is no free trial: the smallest purchase is 1 GB of rotating residential traffic or one IP for one day. Checked on 9 November 2026.

• Sources:
• Proxy302 product facts and price list

FAQ

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