VPS & Dedicated Hosting: Email Blacklisting
Email blacklisting can interfere with your ability to send emails from your server's IP address. There are many email filtering services that blacklist IP addresses. They each have their own criteria for blacklisting an IP address. They also each have their own procedures for getting removed from the blacklist. If you are on a VPS or Dedicated server, you have your own IP address. You will be responsible for removing it from any blacklists it may be on.
- Identifying the Blacklist you are on
- Check Bounce Back messages
- Use a blacklist checking service
- Getting Removed from the Blacklist
To get removed from the blacklist you have to know who exactly is blacklisting you. There are several organizations that maintain email blacklists. The Blacklists are then implemented by email filtering software on the email servers that subscribe to the list.
Usually, the best way to identify which blacklists you are on is to read the bounce-back message of any email that was rejected because of a blacklist. These messages are meant to give you information on why your email was rejected. The wording will not be the same in every message, but you may see some text like the following example:
"Connected to 22.214.171.124 but sender was rejected.
Remote host said: 550 126.96.36.199 is blacklisted at ix.dnsbl.manitu.net"
This means that the IP address 188.8.131.52 is blacklisted by ix.dnsbl.manitu.net, and the email was rejected on that basis.
You can use a 3rd party service to check if your IP address is on any blacklist. However, most services are not able to check every blacklist. You may still need to rely on a bounce-back message to identify any blacklist you may be on. The following link will take you to a popular 3rd party blacklist checker.
Getting removed from a blacklist usually involves contacting the organization that has your IP address blacklisted and following their procedure for removal. Each organization will have a different procedure. The following are some links to the blacklist removal procedures for some common email providers:
- Spamhaus: https://www.spamhaus.org/lookup/
- Trend Micro: https://www.ers.trendmicro.com/reputations
- Anonmails DNSBL: http://anonmails.de/dnsbl.php
- Barracuda: http://www.barracudacentral.org/lookups/ip-reputation
- CBL (Spamhaus XBL): https://www.abuseat.org/
- Cloudmark: http://csi.cloudmark.com/reset-request/
- Comcast: http://postmaster.comcast.net/block-removal-request.html
- Earthlink: http://support.earthlink.net/articles/email/email-blocked-by-earthlink.php
- Manitu: http://www.dnsbl.manitu.net/?language=en
- Proofpoint: https://support.proofpoint.com/dnsbl-lookup.cgi
- SpamCop: http://spamcop.net/bl.shtml
- Sorbs: http://www.sorbs.net/lookup.shtml
Once you are off the blacklist you are going to want to make sure you don't get blacklisted again. Here are a few tips to help prevent blacklisting:
- Security is key! Use strong passwords and monitor your server for malware. Nothing can ruin your email reputation like a compromised email account or malware that sends spam in bulk from your server.
- Don't send too many emails at once. Some services may block you based on the number of emails sent out. The best practice is to limit bulk mailings into small batches and send individual emails out with a few-second delay between them.
- If you are sending bulk mail out, consider using a service that specializes in sending bulk email, such as Constant Contact.
- Make sure your legitimate emails don't look like spam. You can use https://www.mail-tester.com/ to test your email and get recommendations.
- Make sure your SPF and DKIM records are set correctly for your domains.